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PHILOSOPHICAL 



TRANSACTIONS, 



OF THE 



ROYAL SOCIETY 



O F 



LONDON. 

VOL. LXXXI. For the Year 1791. 
PART I. 






<i/.- -" 





LONDON, 

SOLD BY PETER ELMSLY, 

PRINTER TO THE ROYAL SOCIETY. 

MDCCXCI. 



C sa 1 



ADVERTISEMENT. 



TH E Committee appointed by the Royal Society to direA the pub- 
licsition of the FbiUfophical Tranfa£lions, take this opportunity to 
acquaint the Public^ that it fully appears, as well from the council-books 
aad janmals of the Society, as from repeated declarations which have 
been made in fcTcral former Tran/a^ions, that the printing of them was 
always, from time to time, the fingle aft of the refpeftive Secretaries, till 
the Foity^feventh Volume : the Society, as aBody, never intercfling them- 
ielyes any fiirther in their publication, than by occafionally recommending 
the revival of them to fome of their Secretaries, when, from the particular 
drcamftances of their affairs, the Tranfailions had happened for any 
length of dme to be intermitted. And this feems principally to have 
been done with a view to fatisfy the Public, that their ufual meeting^^ 
were then continued, for the improvement of knowledge, and benefit of 
mankind, the great ends of their firft inftitution by the Royal Charters^ 
and which they have ever lince fteadily purfued. 

But the Society being of late years greatly inlarged, and their com<^ 
mnnications more numerous, itwastho\»ghtadvifable, that a Committee 
of their members Ihould be appointed to.reconfider the papers read be- 
fore them, and feleft out of them fuch as they Ihould judge mod pro- 
per for publication in the future TranfaSlions ; which was accordingly 
done upon the 26th of March 1752. And the grounds of their choice 
are, and will continue to be, the importance and fingularity of the fub- 
jefts, or the advantageous manner of treating them ; without pretending 
to anfwer for the certamty of the fafts, or propriety of the reafonings, 
contained in the feveral papers fo publifhed, which muft ftill reft on the 
credit or judgment of their refpeftive authon. 

A 2 It 



Tt Is likcwife ncceffary on this occafion to remark, that it is an cfta* 
blilhed rule of the Society, to which they will always adhere, neyer to 
give their opinion, as a Body, upon any fubjeft, either of Nature or Art, 
that comes before them. And therefore the thanks, which are fre- 
quently propofed from the Chair, to be given to the authors of fuch pa- 
pers as arc read at their accuftomed meetings, or to the perfons through 
whofe hands they receive them, are to be confidered in ho other light 
than as a matter of civility, in return for the refpeft Ibewn to the Society 
by thofe communications. The like atfo is to be faid with regard to 
thefeveral projefts, inventions, and curiofities of various kinds, which 
are often exhibited to the Society ; the authors whereof, or thofe who 
exhibit them, frequently take the liberty to report, and even to certify 
in the public news-papers, that they have met with the higheft applaufc 
and approbation. And therefore it is hoped, that no regard will here- 
after be paid to fuch reports, and public notices ; which in fome inftances 
have been too lightly credited, to thediflionour of the Society. 




v." t:: 



C ONTENTS 



O F 



V O L^ LXXXL P A R T L 

L jf SECOND Paper on Hygrometry. By J. A. Dc Luc^ 
•^^ Efq. F. R. S. Page i 

II. On the ProduSion of Ambergris. A Communication from the 
Committee of Council appointed for the Con/ideration of all Mat-- 
ters relating to Trade and Foreign Plantations ; with a prefatory 
Letter from William Fawkcner, Efq. to Sir Jofeph Banks, 
Bart. P. R. S. p. 43 

III. Obfervations on the J^nity between Bafaltes and Granite. 
By Thomas Beddoes, M. D. ; communicated by Sir Jofeph 
Banks, Bart. P. R. S. p. 48 

IV. On Nebulous Stars^ properly Jo called. By William Hcr- 
fchel, LL.D. F. R. S. p. 71 

V. Abftra6i of a Regijfer of the Barometer^ Thermometer^ and 
Rainj at Lyndon in Rutland; by Thomas Barker, EJq.; 
with the Rain in Hampfbire and Surrey; for the Tear 1789.. 
Communicated by Thomas White, Efq. F. R. 51 p. 89 

VI. Obfervations on certain horny Excrefcences of the Human 
Body. By Everard Home, Efq. F.R»S. P* 95 

VII. Con- 



vi CON TENTS 

VII. Confideratlons on the Convenience of meafuring an Arch of 
the Meridian^ and of the Parallel of Longitude^ having the 
Obfervatory of Geneva for their common InterfeSion^ By 
Mark Auguftus Pi£tet, Profejfor of Philofopby in the Aca^ 
demy of Geneva \in a Letter to Sir Jofeph Banks, Bart^ 
P. R. S. p. io6 



APPENDIX. 

Meteorological Journal kept \ at the Apartments of the Royal 
Society^ iy Order of the Prefident and Council. p. i 




CONTEN T S 



OF 



VOL. LXXXI. Part II. 

Vni. /\Nthe Rate of Travellings as performed by Camels ; and 

its Application^ as a ScaUy to the Purpofes of Geogra^ 

phy. By James Rennell, Efq. F. R. S. Page 129 

IX. On Infimte Series. By Edward Waring, M. D. F. -R. .SI Luca- 
£aii Profejfor of Mathematics in the Univerfity of Cambridge. 

p. 146 

X. An Account offome Appearances attending the Converfon of 
cafl into malleable Iron. In a Letter from Thomas Beddoes, 
M. D. to^ir Jofcph Banks, Bart. P. R. S. p. 173 

XI. On the Decompofition of Fixed Air. By Smithfon Ten- 
nant, Efq. F. R.S. p. i8z 

XII« A Meteorological Journal^ princtpally relating tet Atmo^ 
fpberic EleSrkityi kept at Kuightlbridge, yro/s the ^tb of 
May, 1789, to the Stb qf May, 1790. By Mr. John Read; 
€<mmunicatedby R. H« A« Bennet, Efq. F. R. S. p. 185 
Xin. Farther Experiments relating to the Decompofition of 
depblogifticated and infammabie Air. By Jofeph PriefUey, 
LL.D.F.R.S. p. 213 

XIV. Expe- 



iv CONTENTS 

XIV. Experiments on Human Calculi In a Letter from Mr^ 
Timothy Lanei F. R. S. to William Pitcaim, M D. 
F. -R. S. p. 223 

XV. Chermes Lacca. By William Roxburgh, M. D. of 
Samulcotta. Communicated by Patrick RufTell, M D. F. R. /SI 

p. 229 

XVI. T^he Longitudes of Dunkirk and Paris from Greenwich^ 
deduced from the Triangular Meafurement in 1787, 17^8^ 

fuppofing the Earth to be an ElUpJoid. By Mr. Ifaac Dalby ; 
communicated by Charles Blagden, M. D. Sec. R. S. p. 236 

XVII. On tie Method of determining^ from the real Probabilities 
of Life^ the Values of contingent Reverfons in which Three 

' Lives are involved in the Survivorjhip. By Mr. William 
Morgan, F. R. S. p. 246 

XVIII. AbjiraS of a Regifter of the Barometer^ Thermometer^ 
and Rain^ at Lyndon in Rutland ; by Thomas Barker> Efq. ; 
with the Rain in Hampfhire and ^Mxity \ for the Tear 1790. 
Communicated by Thomas White, Efq. F. R. S. p. 278 

XIX. Defer iption of a jimple Micrometer for meafuring fmall 
Angles with the Telefcope. By Mr. Tiberius Cavallo, 
F.R.S. p. 283 

XXL Experiments and Obfervations to inve/lfgate the Compofition 
of James's Powder. By George Pcarfon, M. !)• F, R. S. ; 
communicated by Sir Jofeph Banks, Bart. P. R. S. P* 3^7 

XXII. An Account of fonie chemical Experiments on Tabaflieer. 
By James Louis Made, Efq. F. R. S. p. 368 

XXIII. A Second Paper en Hygrometry. By ). A. Dc Luc, 
Efq. F. R. S. p. 389 



ERRATA. 



VOL. LXXX. 

p. 598. I. I4» fi^ 307366.8 nad 303766.8 
610. !• 20* for p. 224 read p. 244. 

Alfo in Gen. Roy*s Tabic of Genial Re/uks^ p. 232, longitude of Wrotham 
Hill, /^r 19.12 rwrf 18.48. 



I ^ f ^5 ^^ ^«*^ '^ * 




i|^^^#iij^*<gl^^^JA^»l^»^|f^^^i^A^^^W^^W^Hi^#^^^Hi^#i^ 



PHILOSOPHICAL 



TRANSACTIONS. 



L -^ Second Paper on Hygrometry. 
JBy J. A. De Luc, JE/^. F. R. S. 

Read December 9, 1790. 

IN a Paper which I had the honour to prefent to the Royal 
Society in the year 1773, I Ikctched the following propo- 
fitions, as fundamental for the conftrudtion of an hygrometer. 
I ft, That^r^, confidered as the caufe of Am/, was the only 
agent by which abfolute drynefs could be immediately produced 
(§ 5.). ad, That water^ in its liquid ftate, was the only fure 
immediate means of producing extreme moifiure in hygrofcopic 
bodies (§ 8. andy&y.). 3d, That there was no reafon, ^ priori^ 
to cxpeft, from any hygrofcopic fubftance, that the meafurable 
Vol. LXXXI. B effeds 



2 • Mr. DE Luc on 

effects produced hi it by moljiure were proportional ta the in* 
tenfities of that caufe ; and, confequently, that a true hygro^ 
metrical fcale was to be a particular objedt of inquiry (§ 2.)». 
4th, lafHy, That perhaps the comparative changes, of the 
dimenfions of a fubftance, and of the weight of the fame or 
other fubftance, by the fame variations of moifture^ might lead 
to fome difcovery in that refpeft (§ ya.^f. The fan^e propofi'- 
tions will be the fubjedl of this Paper. ' 

Of abfolute arynefi. 

I . An hygrofcopic body, which is not brought into contact 
with any other body drier than itfelf, cannot lofe any part of 
its moijlure but by evaporation ; and if this is intirely produced 
hyjire, there may be fuch a degree of heat as will caufe the 
total evaporation of that moijlure. This is the principle on 
which the above firft proportion was founded ; but at the fame 
time I mentioned, that I had not brought it into praSice, be- 
caufe of the impoffibility of fubmitting the fubftance of the 
hygrometer to fuch a degree of heat. However, I foon removed 
that difficulty by confidering, that the degree of heat neceflary 
to produce extreme drynefs^ might be applied to fome fubftance 
that could bear it ; and that drynefs be tranfmitted to the hygrc^ 
meter^ by inclofing it with that fubftance in a proper veflel. 
The fubftance I ehofe was potajh ; and I prepared, for this and 
Ibme other hygrometrical purpofes, an apparatus which was 
made by Mefl". Nairne and Blunt ia 1776. But anew 
objedlion ftopped me again in that purfuit, and led me for fome 
time to a very great and now almoft ufelefs labour. The 
degree of drynefs produced by potajh fo ufed, could be only 
proportionable to the degree of heat that it had received ; and 
q not 



Hygrometry. ^ 

not conceiving yet any known limit to the inlenfity of heaty 
I could not cxpeft any limit to drynefs^ nor even a fixed degree 
of it. 

2. I remained at that point, with however a comparable hy- 
grometer laborioufly conftruded, till I came to conceive, that 
beat muft be at its maximum in a body, when it is incan^ 
defcent ; which opinion I have explained in my work, Idessfur 
la Mithrologie. • From that firft idea I foon after concluded ; 
that every hygrofcopic fubftance, which could retain that pro- 
perty after having been brought into, incandefcence^ would 
anfwer my firft purpofe. The following is the theory refult- 
ing from the whole of the above confiderations. ift, The 
hygrofcopic fubftance which has the moft capacity for moijlure^ 
and receives it the moft readily, being placed in any quantity iu 
a given fpace, cannot bring that fpace.to a degree of drynefs 
greater than its own ; and if that degree is undeterniined, it 
cannot afford any Jixed paint for the hygrometer. 2d, The 
hygrofcopic fubftance which has the fmalleft capacity for moif^ 
ture^ and is the floweft in receiving it, if it is really reduced to 
extreme drynefs^ will have the power of producing it in a given 
fpace, provided its fmall capacity be compenfated by a greater 
quantity, and its flownefs by more time. 3d, Every hygro^ 
fcopic fubftance, which may be brought to white heat without 
loiing its property, is fit to produce extreme drynefs in a clofe 
ipace. 4th, It is indifferent for that purpofe, that the fub- 
ftance ufed be of the clafs which has a chemical affinity with 
ivatery it being fuflicient that, after having been reduced to 
extreme drynefsy it be ftill capable of receiving it from the am- 
bient medium^ as may every porous fubftance. 5th, But for 
the practical purpofe of fixing the point of extreme drynefs oh 
hygrometers^ fuch a fubftance muft be chofen as, with a great 

B 2 capacity 



4. Mr. DE \j\Jzon 

capacity for moljiure^ receives it but flowly : as by that firft pro- 
perty it may be taken in lefs quantity ; and by the laft, it will be 
lefs fubjedt to acquire a fenfible quantity of moijlure in the time 
neceflary for the operations. 

3. Pot'Opj and fome other alkaline fubftances afforded the 
firft of thofe properties, but not the laft ; and I had not fixed 
on any fubftance, when, being at Birmingham in the aittumii 
of 1782, Mr. James Watt informed me, that his friend Dr. 
Black had fouiid in quicklime a great capacity for moijlure^' 
and much flownefs in retaking it : this he knew, by having 
kept a long time the fame lime in a clofe veffel, for drying falts 
and capillary tubes for thermometers. Thefe were the very 
properties I wanted for my purpofe, which thereby I executed 
as foon as I came home. I made thofe firft operations in fmall 
glafs veffels, ufing old //W, which I brought again to white 
heat every time I ufed it. Thefe firft trials agreed with my 
theory in its firft point; that of producing conftantly the fame 
degree of drynefs : as for the fccond, namely, whether that 
degree was extreme^ it depended on other experiments. 

4. Being fure then of a fixed degree of drynefs, the number 
of experiments I undertook made me wifli for a means of 
avciding the frequent repetitions of bringing again my lime to 
white heat ; and having found one which has fucceeded, I am 
going to defcribe the apparatus. The veflel, fig. i. is of tin, 
3 feet high and i in diameter. A glafs plate a^ a^ Ui a^ is £xed 
at the top, forming a vertical feftioii of the cylinder at i 
inch diftance forwards from the axis. A ^woven braf^-^wire 
cage ^, hj b^ h^ is fixed in the veflel through its diameter, in 
order to keep a fpace for the inftruments ; for the fainc pur- 
pofe it is open at the top, and alio oppofite the glafs, where 
the dials of the iaftrumeats are to be feen« For my experi- 
ments^ 



IIygromeiry4 j 

ments, which required iiiftruments of various (izes, I made 
that cage i8 i/iches high and 2 deep; but it may be much 
Itnaller for common hygrometers. The whole veflel, except 
that fpace, has been filled, through the openhigs c, r, with 
quicklime taken from the kiln, and fufFered only to lofe .the 
red heat ; after which the openings were covered with heaps of 
the fame lime, which abforbed the moifture of the air entering 
the veflel while it was cooling, and then the openings were 
fhut whh tin plates and putty. The top of the veflel has four 
fquare openings /, d^ d^ d, correfpondcnt to the wire cage, for 
the introdudion of the inftruments, which are hung to hooks. 
I ufe a hooked wire for putting in or taking out the inftru- 
ments, to avoid bringing my fingers near the openings. Thefe 
arc kept (hut with tin plates and putty : I never open but one 
at a time, which I leave open as little as poflible ; and to pre- 
vent the introdudion of the external air in thofe (hort opera- 
tions, 1 make them as nearly as poflible at the fame tempera^* 
turc, which being 60° of Fahrenheit may be obtained iix 
every feaibn. With thefe precautions, and alfo by moift air 
being lighter than dry air, there is fca,rccly any moifture intro- 
duced in the veflel except by the inftruments themfelves« 

5. This application of my method afforded. me a very ftrong 
confirmation of the pradlical fixity of the point of drynejs pro- 
duced in that manner by lime : for the apparatus was different 
from the former ones ; i ft, by the quantity of the //W; ad, by 
the lime having been put very hot into the veflel, while, when I 
vfed glafs veflels, I had Cuffered it fometimes to cool down to 
60** ; 3d, by that lim^ being of the firft calcination, inftead of 
old lime brQught again tp white heat ; and all thefe differences 
produced no fenfible effect on the point of drynefs. Since that 
time Mefl*. Nairn£ and Blunt, Mr. Hurter, and Mr. 
^ Haas, 



6 Mr. Dfi Luc on 

Haas, have made apparatufes of the fame kind, and I have 
made myfelf fome others of different fizes and (hapes ; and 
they all produce fenfibly the fame degree of drynefs. 

6. The defcribed apparatus was ready in the month of Ofto- 
fcer, 1787, and I put in it one of my Hr^ hygrometers % which, 
in a few days, came to its fixed point of drynefSj and there it 
has remained ever fince, though I have opened the veflel above 
four hundred times. That degree of conftancy, much beyond 
my expedlation, has enabled me to make a variety of ex- 
periments, which elfe had been next to impoffible : it pro- 
ceeds partly from the great capacity of quicklime for moijlure^ 
which I (hall determine hereafter ; and partly from its flownefs 
in receiving it ; which circumftances, added to the fmall fize of the 
openings, to their being at the top of the veffel, and to the care 
of putting in and taking out the inftruments nearly at the fame 
t-cmperature, prevents the lime from acquiring any fenfiblc 
degree of moijiure during thefe operations. 

7. I did not truft at firft the apparent continuance of the 
fame degree of drynefs in that veffel. At the end of nine 
months of frequent ufe, I began to fear^ left the whalebone^ 
of which thtjlandard hygrometer is made, had been impaired ; 
and I took it out, to try its point of extreme moifture (of which 
I (hall fpeak hereafter ;) but it came exadly to that point, and 
when put again into the lime-ve(rel it returned where it ftood 
before. I have repeated many times that trial, with the fame 
refult ; the la(l time was at the end of three years, when, 
inftead of a lofs of expanfibility in the whalebone^ I found a 
fmall increafe, but probably accidental ; it went a little farther 
than its point of extreme moijiure^ and came back to its con- 
ilant point of drynefs. 

8. The 



Hygrometry. j 

8. The principles of hygrometry being now ray only objeft, 
it would not be proper to enter into particulars on its praftical 
part; but I ftiall here mention for once, that the fteadieft hy^ 
grofcopic fubftances are fubjeft to anomalies : for inftance, after 
an hygrofcope has remained fixed in water for many hours, if it is 
taken out, fufFered to dry a little, and then put again iwlo water ^ 
It may fometimes happen to overpafs that point. In the 
fame manner, after an hygrofcope has been long fixed in the 
lime-veflel, it may happen alfo, that in taking it out only for 
ia quarter of an hour, and putting it in again, it will move a 
little farther than it was before. Again, if in taking it out of 
the Itme^niejfel^ where it had long remained fixed, it is put into 
water^ and then back into the Ume-vejfely it may happen, that 
it will fix itfelf a little (hortof its fbrnier point, and never move 
thence, except by repeated great variations of heat ; but if, when 
it (hews that difpofition, it is taken out for a (hort time, and put 
in again, it will then attain its ufual point. This was the 
cafe in the laft trial of myjiandard. Laflly, the fame anoma- 
lies may take place at every other point of the fcale of every 
hygrofcope, only more or lefs according to the fubftances; 
fbme of which, for that reafon, cannot be ufed for pradlicat 
hygrometry. 

9. Thofe anomalies of the fteadieft hygrofcople fubftances^ 
will probably prevent our ever having in the hygrometer an 
inftrument nearly fo exaft as the thermometer ; and this I was to 
premife, that when I mention the refults oii^^slxzxAsxIyygroJcopic 
experiments, it may be underftood, that they have only the 
degree of exaftnefs that belong to their clafs. Luckily thofe 
anomalies are yet of no confequence for the great objefts of 4y- 
grology and meteorology i the prefent ftate oi hygrometry being fuf- 
ficient to excite on thofe obje(Sls,queftions of great importance for 

natural 



8 Mr. DE Luc on 

natural phllofophy. And in the mean time thofc anomalies 
are very interefting in thcmfelvcs ; as, from their laws, they 
feem to point out Ibme modification of cohejion^ as being the 
immediate caufe of elajiicity mfolids. If I can find time to put 
in order a number of obfervations and experiments I have 
made in that refpe£t, I intend to make it the fubjeft of a 
Paper, in which I Ihall examine, from a general refult of 
thofe phaenomena, the comparative ufe of weights and fprings 
for keeping ftretched the hygrofcopic fubftance in hygrometers. 

lo. After jixity in the degree of drynefs produced by lime 
in the manner I have explained, the next point to be examined 
in refpeft of my theory, was, if the nature of the fubftance 
brought to a white heat, had any influence on the degree of 
drynefs thereby produced ; and in order to try at once the efFed 
of a very great difparity, I chofe fuch a fand-Jione as is not 
afFefted by acids ^ and ftrikes fire from fteel, before and aifter 
having been incandifcent. The firft experiment I made was . 
with a view of finding the comparative capacities for moijiure 
between that Jione and lime. For that purpofe I took fuch 
pieces of them as might be readily reduced to half an ounce 
while incandefcent ; which being done, I put them into brafs 
cups, fitted to a fcale, and I inclofed them under a 
glafs veflTel inverted over water. I weighed thofe fubftances 
from time to time ; each of them continued to acquire weight 
during five weeks ; at which time the fand-ftone had gained 
^4^ part of its original weighty and the lime 4.J.4 : this kft was 
at that time ;ill cracked and fallen in fmall fragments, eafiljr 
reduced to powder; the fand-ftone {{ruck fire as before^ I next 
prepared a cylindrical tin veflel, lo inches in diameter and 14 
inches high, with a glafs top, which I filled with fragments 
of th^t ftone^ treated as the lime ; and when it was cooled^ I 

4 ^ put 



Ifjgromeiry. p 

pit into It an hygrmneier^ whofe fixed point of drynefs has been 
taken in the lime apparatus : and in five weeks it was fixed to 
the fanae pouit. This is a demon (Iration, that the nature of the 
fubftance does not interfere with the degree of drynefs produced, 
and that incandefcence is the only caufe of its fixity. 

11. Lailly, in refpeA of bygrometry, a degree of drynefs thus 
determined might have been fufficient ; but for fygrohgy^ 
and even for natural philo(bphy in general, it was defirable to 
difcoyer if th^t fixed degree of drynefs was alfo abfolute i and the 
following are the confiderations which directed me in that en« ' 
quiry : if evaporation is produced by heat only, and if incan^ 
defcence is the maximum of beat ; an bygrofcopic body, which 
is brought to incandefcence^ cannot contain any evaporable water ; 
and if that body has fuch a mafs, as to be capable of abforbing 
all the water fV/i^r^W in a certain fpace, without acquiring any 
meafurable moifiure^ that fpace may be called abfolutely dry. 
Now, if an bygrofcopic fubftance which is inclofed in that fpace, 
contains any fenfible quantity of evaporable water, when beat 
increafes, that fubftance muft lofe a part of its moifiure in the 
medium^ and take it back by the diminution of heat. Confe* 
quently there was a means of difcovering, if bygrofcopic fy^hfi^nccs^ 
reduced to the above degree of drynefs^ ftill retain a fenfible 
quantity of evaporable water ; it was that of obferving their 
wf/^A/, by changes of heat: and from thefe previous confiderations 

I made the following experiments* 

12. I hung fucceflively to a very {cnfiblc beam^ (hewing the 
changes of weigbt by an indexj ditfcrent forts of vegetable and 
animal fubftancef, the beam being inclofed in a glazed tin- 
vefiel, containing a fufficient quantity of quicilime; and dur* 
ing the operations, I produced from time to time great changes 
in the temperature of the vcffcl. As long as thefe fubftances 

Vol. LXXXI. C retained 



lo Mr. DE Luc m 

retained a fenfible quantity of evaporable water, the incrcafe cf 
beat made them lofe fome weighty which they regained partly 
when the heat returned to the fame point. But that eflfefl: di- 
miniftied by degrees ; and, at laft, a change of 30° of Fabren^ 
belt did not produce any fenfible change of weight in thofe 
fubftances, though they were fuch as had a great capacity for 
moijlure. An hygrometer placed near the beam^ was then at 
the point taken in the lime-veJfeL That finglc experiment con- 
firms all the previous con (iderat ions from which I had expected 
abjolute drynefs from incandefcence. 

Of extreme motjlure. 

13. The fecond proportion I had (ketched in my firft paper, 
is this •* that water ^ in its liquid ftate, is the only fure immediate 
** means of producing extreme moijlure in hygrofcopic bodies,*' 

14, Moijlure^ the nature of which we are firfl: to determine, 
may be coufidered in three different cafes. — ifl. In fubflances 
which have an affinity with water ; by which their molecUlae 
and thofe of water may unite, and form a new compound. — 
2dly, In fubflances which have no affinity with water ^ but to 
which water has a tendency to adhere; by which caufe it 
enters their capillary pores. — jdly. In the medium^ or fpace free 
from viiible bodies. I have not undertaken to difcover what, 
in the firft of thefe cafes, might properly be called /w^^wr^, and 
its degrees ; as 1 forefaw great difficulties in that undertaking, 
which befides was unnecefTary to my principal purfuit : 
therefore I come immediately to the fecond cafe. 

15. When I wrote my vfovk Idees fur la Mitiorologie^ having 
not yet made fome experiments I had in view to verify the opi- 
nion I entertained, that vegetable and animal fubftances, as 

well 



Uygrometry. 1 1 

well as the porous mineral ones, received water merely by the 
faculty oi ^capillary pores j I ufed fometimes the expreffion hy^ 
grofcopic affinity^ in treating of the bygofcroptc equilibrium ; but 
before that work was come out of the prefs, having converfed 
on that obje£t with Dr. Blagden, and found him inclined to 
that opinion, I had time and opportunity to exprefs it, in 
§ 276, as follows : " There are reafons to doubt, whether fome 
** of the fubftances, which (hare amongft them the water dif- 
^^ feminated in a fpace, do not fuck it, by a faculty (imilar to 
«* that of capillary tubesj without any chymical affinity with 
*• water.^^ That opinion will be now confirmed by the fol- 
lowing experiments. 

16. 1 ft. Exp. Sugar has an affinity with water ^ and no fen- 
fible one with alcohol : however, a lump of fugar will imbibe 
this laft liquid as readily as the firft. Confequenrly, water is 
not imbibed by fugar in confequence of their affinity ; fince 
alcohol is alfo imbibed : they both afcend in Jugar^ by the faculty 
of its capillary poreSy as they do in fand^Jone or in fpunge. 
But when water has thus entered Jugar^ it dijfolves it ; which 
then is a chymical eflFed ; whereas alcohol evaporates, and leaves 
the fugar fenfibly as it was before. 

17. 2d. Exp. If wj/^r penetrated hygrofcopic fubftances of 
the vegetable and animal kinds, by an affinity with them, it 
would not be natural to pxpe£t, that other liquids^ which do 
not (hew an affinity with the fame fubftances as water ^ (hould 
penetrate the above-mentioned fubftances. Being led by that 
confideration, I made two fygrofcopes of different elaftic animal 
fubftances; and after having marked the point where they 
ftood in water^ I immerfed them fucceflively in alcohol and in 
ether ; by which liquids they were expanded nearly as much as 
hy water ^ and they contraded as much in coming out of them. 

C 2 In 



1 2 Mr. OS Luc on 

In thofc experim^tits a (ingular phatnomenon happened in both 
hygroicopes. The firft efieA of the tmtnerfion of thofe animal 
fubilances in alcohol (and I fuppofe it would have been the fame 
with vegetable ones) was contraSlionj fbon fbUbwed by e^panfioni 
and when they came out into the air, the firft effeA was expanfitm^ 
foon followed by contraSion. The caufe of that reciprocal pfaae-* 
Domenon is undoubtedly the effiaity of alcohol with 'water. In 
the immerfioD, fome of the tmifinre caoie out of the fubftance^ to 
unite with the furrounding alcohol i by whkfa lofs oi water ^ zc0fH 
traSlhn took place in the fubftaace, 'till it came to imbibe the 
alcohol itfelf. In the immerfion, fome of the moifture o€ the 
air, uniting immediately with the alcohol retained by the fob* 
fiance, expa^ided it to the fame degree as if it had been in watery 
after which, the alcohol evaporating, the fubAanca contra£bed» 
Thofe phacnomena did not happen with ether ; thia not unitiag 
readily with 'water ; but it expanded thofe fubftances as much 
as alcohol^ and nearly as much as water. From thofe pheno- 
mena we toay conclude, that the penetration of animal fub« 
ihnces by water ^ and coufequently by moifture^ is produced^ as 
that of Jiigar^ fand-Jlone^ and every other porous fubftance^ by 
the faculty of capillary pores^ without any i^ity between theoi 
and water ^ 

1 8. 3d. Exp. In that theory, of a mere imbibition eA water 
by hygrofcopic fubftances of the elq/lic kind, a cirottmilance, 
which feems to point out affinity f. was to be explained ; it is that 
of the hygrofcopic equilibrium.. In view of that ok^eft^ I made 
the following experiments, not newin themfelves, but dtrededto 
my purpofe. I took fome glafs tubes, of different fmall bores^ 
which I firft bent in the fhape of fyphons ; after which I cut 
them in the middle of the bent part. This was to enable me, 
to bring intoexa£t communicatioa the lower end t)£ two tubes» 

though 



V diougb held tn a rertical politico, as an inverted fyphon O^ig. z,) 
VTIk following are the experiments.--* i ft. Exp. When a colunon 
lof the liquid had afcend^d in one of thefe tubes ; if I applied to 
it an enoptj tube of the fame bore, the iiguid column divided it* 
ielf equally between them.— 2d. £xp« When the empty tube 
was of a fmaller bore, that column rofe more in it, than it funk 
in the other ;. and the contrary happened when the empty tube 
was of a larger bore. — 3d. Exp. When fome more liquid vtz% 
fttpplfcd to the united tubes, it rofe in both, in proportion to 
the refpediw heights of the former columm. — 4th. Exp. When 
a fuperabundant quantity of Ufuid was fupplied, it rofe to a 
maximwm in each tube, and the heights of the columns ^ 
jocreafed va fome proportion with their former heights. 

19* Thefe known fadts have a clear analogy with the 
fygrofcofnc equilibrium in elqftic fobHauces.^— x ft. Case. When. 
the quantity of Rquid common to capillary tubes is not fuffi- 
cient for them to receire their refpe£live maximum^ they fhare it ^ 
between tbemt and the equiUbrium takes place^ when there is, . 
in each of them, thefame ratio between its fpecific capillary power 
andtheweigbt of the raiied column*In the fame manner; when the 
quantity oi water diffeminafced in a fpace, i& not fofficient^ for 
leveral hygrofcopic fubftances to receive the maximum of water 
which they can contain in their pores ^ they fliare it amotigfl them ; 
and the equilibrium is produced, when there is in each of them 
the fame ratioy between its fpecific capillary ponvtr^ and the 
refiftance of their pores to be more dilated.— -ad. Case. When 
there is a fuperabundant quantity of liyuid common to fome 
c&pillary tubesj each of them receives its maximum; which is 
determined by an equilibrium^ between its total capillary 
/0tivr, and the weight of the raifcd column. In the fame man- 
ner, when there is a fuperabundant quantity of nvater common « 

to 



14 Mr. DE Luc on 

to feveral hygrofcopic fubftances, each of them receives its 
maximum \ which is determined by the equilibrium^ between 
their total capillary power^ and the refiftance of their ^or^j to be 
more dilated. That final equilibrium^ which, from its very nature^ 
cannot be overpaffed in any elafiic fubftance properly ufed, 
determines the fpecific capacity of thofc fubftances for moijiure. 

20. Mot/lure then, confidered in porous bodies not Joluble 
by water ^ may be defined, ** A quantity of loater^ which is 
" invifibly contained in xYitxv pores ; without any other connec- 
" tion with their fubftance, than that which it has with the 
** glafs of the capillary tubes into which it has afcended/' 

2 1. We may fee now whence proceeds the hygrofcopic equili-^ 
brium between elaftic fubftances inclofed in a fpace, either 
filled with air or deprived of it. In this explanation it is 
unneceftary to determine, how water is invifibly diffeminsAed in 
fpaces free from vifible bodies, therefore I (hall not enter here 
into this fubje£t ; that di^emination is a fa£t admitted in eveify 
hypothefis, confequently the medium is only to be confidered as 
the ftock and ftandard of moijiure. By the caufe, whatever^ of 
evaporation^ .hygrofcopic fubftances lofe or gain water in the 
medium^ according to its degree of moifture^ till they are in 
equilibrium with it; which implies the equilibrium amongft 
themfelves according to the laws refulting from their own 
nature. 

22. Now moifture^ in a general fenfe, will appear to be, *< a 
** quantity of invifible water ^ either evaporable^ or evaporated^^ 
And from that definition, the maximum of moifture will exift, 
when, ** every circumftance remaining the fame, no more 
^^ water can be admitted in a fpace, without becoming vifible ; 
^^ on y^//^ bodies, by their furface being weti and in the medium^ 

4 ^•by 



Hygrometry. 1 5 

**bya {pont^neous precipitation ofivater.^^ Laftly, as immerfing 
Iblid bygrofcopic bodies in water ^ or e:^po{ing them in a medium 
where there is an aftual precipitation of water (as in a fog^ is 
an efiedual means of funiilhing their p^^res with the whole quan* 
tity of water they can imbibe ; it is evidently a Jure means of 
producing extreme moijture in them : and this point cannot be 
overpaiTed, neither in water^ nor in fog^ fince it depends upon 
the re^/tance of the pores to further dilatation by the mere intro» 
duSion of water ; but it muft be attained in an hygrometer^ to 
fix its point of extreme moifture. 

23, When formerly I had fixed upon that method for pron 
curing to my firft bygrorneter a true point of extreme moifture^ 
it occurred to me, that the temperature of water might in- 
fluence fenfibly the expanfion of its ivory tube ; and in order to 
difcover if it was fo, I made fome experiment s^ related in 
§§ 104 &c. of my former paper, the refult of which was, 
that the temperature of water had a fenfible efFedl on the expan- 
fion of ivory. But foon after I diflruited fome modifications of 
that complicated hygrometer ; and efpecially this particular 
refult. 

24. I then changed that firft method ; which confifted in 
meafuring the changes of capacity of hollow cylinders, into 
that of meafuring the changes in length oi hygrojcopic fubftances; 
and for fome preliminary experiments on many of them, I 
made particular yr^/n^j, in which, by a combination oiglafs and 
brafs^ the ene£ts of heat on thofe materials compenfated each 
other ; by which means the indices of thofe inftruments were 
only affeded by the modifications of the bygrofcopic fubftances 
tried in them. I have mentioned thefe frames in a paper on 
fytometryj printed in the Phil. Tranf. for 1778. With thefe 
frames I firft tried ivory^ in . water of different temperatures ; 

and 



if6 Mr. DE Luc on 

and I found a very little difference in its exfanfim^ comparatively 
with what had appeared from my firft experiment. Then, 
continuing the fame trial on various fubftances, I, found the 
effeft of different temperatures of water very fmall in general ; 
and even in fome fubftances, as deal taken lengthwtfe, and 
bemp^ I could not afcertain any. 

25. Thefe experiments led me to think, that the fmall 
variations produced by heat in hygrofcopic fubftances dipt in 
nvaierj were not hygrofcopic modifications, hot the mere efie£U 
of heat^ by the ceflation of all hygrofcopic modifications ; thele 
having then attained their maximum: which is a difcrimination of 
effedsy that I had vainly attempted to produce by other means. 
When' afterwards I had found the method of producing atrtme 
drynefs^ I made a lime apparatus, for the purpoie of repeating 
in it the fame experiments with my compomui frames ; and 
I fouQd that theory confirmed,^ by the effeds of heat in 
that apparatus being nearly the (ame, on the fame fubftances, 
as when they were in water. 

26. From the whole of the foregoing experiments there 
cannot remain any doubt, that water^ in its liquid ftate, is a 
fure means of fixing the point of extreme moifture on hygrometers. 

Particularly, in refpe£l of elaftic fubilanccs, as ivory, ^///^ 
whakbone^ all forts of wood, and a number of others which I 
have tried, the lafl: experiments in water of different tempera^ 
/«r£j, afford an immediate proof, that their iicoXtj oi fuckis^ 
water has a fixed limit, proceeding from a final refiftance of their 
pores^ to be more dilated by the introduduoa of water. Coiiie* 
quently, their utmojt expanfion is a true fign, that moiftwre n 
extreme in them ; which point cannot be exceeded. But my 
propofition extended farther : 1 had faid, that water was the 
mly certain means of obtaining immediately the point ot 
2 extreme 



Hygrometry. 17 

extreme moifture on hygrometers ; and this is a moft important 
queftion, both of hygrometry and hygrokgy^ which remains 
to be examined. 



On /iJ^ maximum of evaporation, and Its correfpondence with the 
maximum of moifture in a medium, 

27. Since moifture confifts in invijible water, an excefs of 

water is the only immediate means of afcertaining that the 

maximum exifts ; as, if a refer voir is above our reach, the only 

means of knowing if it ht full of water, is when it overflows* 

From that principle, a fog gives the point of extreme moifture 

on hygrometers J like water itfelf; becaufe it covers very 

foon the hygrofcopic fubftance with a coating of water : fome* 

times even it expands it a little more than an immediate appli« 

cation of water ; but this belongs to an objeft that I have 

waved before, as relating to fome modifications of elaftic fo* 

lids (§ 8.). No other means then but an excefs of water over 

the furface of the hygrofcopic fubftance of the hygrometer ^ can 

afcertain that it is arrived at its point oi extreme moifture ; and the 

firfl immediate demonflration I fhall give of it, will be afforded 

by dew ; a very uncertain, though apparently certain fign of 

extreme moifture in the air. We fay, that there is dew^ when 

fbme folids expofed in the open air in a clear evening are wet ; 

but if that was the efFefl: of a precipitation of water happening 

in.the /?/r, all the folids thus expofed would be wet\ which is 

far from being the cafe ; ccHifequently, that phenomenon muft 

proceed from fome particular caufes, by which, though no 

water is yet difpofed to abandon the medium^ it gathers on fbme 

particular folids. It is very long fince the phenomena of dew 

have perplexed natural philofophers ; and they were the firft 

VoL^LXXXI. D which 



J 8 Mk Dfi Luc en • 

which I ftudied in the bfegiiinitig of my rcfcarchcs ia meteoro^ 
logy ; but all thtit I concluded ftiom my cxperitaents and ob^- 
fervations was, that we could not underftand thpfe phaciKHnena 
without firft having a fure hygrometer. This is the rcafou 
why, foon after 1 had made my firft hygrometer^ I expofed it 
in the open air iti the country, fufpended very little above the 
grafs, from the morning of a fine day to the time of dew in 
the (evening ; the gra/s grew wet^ and the hygrometer r6aiained 
at a great diftance froih the point which had been fixed in waters 
I have related that experioient in § 9 li, of my firft P^per. 

28. When I bad made hygrofcopei of Various forts o{ JUps i 
for inftance, of different woods and of whaktone^ cut acrofi 
the fibres ; of ivory attd horn^ reduced firft into thkn tiibes^ 
and then cut in fcrcw 5 and of quilis^ by cutting alfo in fcrevr 
their barrels ; I repeated, with thofe inftrumeiHs, my ob(er* 
vations ati dew ; land to give a ihort^ but determinate idea of 
the phenomena I obferved, I -fliali reduce them to fome gene* 
tal cafes, as indicated by one only of thofe hygrojcope^^ that of 
jw///, which, like all the others, is divided into 100 parts, frottt 
extreme drynefs to extreme moijiure. Thcfe hygrofcopcs i^ofe 
fufpended in the open air, three feet above a grafs-plat \h the 
country, ift Cas£. When a clear and calm evening fucCeeds 
to a clear and warm day, the grafs frequently grows w?/, 
though the above hygrofcofe ftands many hours, and fbinetimes 
the whole night, between 50 and 55. 2d Case. If the dew 
increafes, fo that taller herbaceous plants and Jhfubs grow wrf 
In fucceflion, the hygro/cope moves more and more towards 
moj/ture ; and when it is come to about 80, plates of glafs and 
oil-paint alfo grow weti but at that pcficd, neithw metallic 
plates, expofed like the glafs ones, nor forbe Jbrubs and 1rees^^ 
are wet ; aiid this ^\&x may laft whole nighcs. 3d Cafe, li the 

dew 



Jlew proceeds to Its maximum^ the hygrojcope moveS from Bo to 
foo (and fometimes a little farther, § 27.). Then we hav« 
alfo a certain proof that extreme moijiure exifts in the air ; fojf 
•very fblid body expofed to4t is wet. But it is only at that 
moment that we can depend on extreme molflure exifting ; for, 
if in the other dcfcribed ft^ges of the phaenomenon, the ap- 
pearance of water on the furface of fome folids hsld proceeded 
from a fpontaneous precipitation in the air, all the other folids 
ought to have been wet ; but they only become wet in a certain 
fuccefflon, and in the mean time the flip oiquilU and all the other 
^above-mentioned bygrojcopes^ move more and more towards their 
point 100, in fign of moijlure increafing in the air. Confe^^ 
quently (as I had concluded from my firft obfervations), in- 
flcad of having in dew an bygrojbopic ftandard for the hygrome* 
ter^ we have in its phajnomcna many circumftances which 
will only be explained with the afliftance of that inftrument* 

29. Some previous obfervations had alfo warned me againft 
the general idea, that moifiure was to be todreme in the air^ 
when there was a fufficient quantity of water in the fpace^ 
iBven though that air might be fuppofed to be filled with map(h- 
rated water to its maximum ; and the doubts I entertained in 
that refpeft were the caufe of the difficulties! exprefled in the 
•beginning of my firft Paper, which I only got over when I 
thought of water itfelf, to bbtain the point oi extreme moifturi 
on my hygrometer. This was alfo the reafon why, as foon as 
toy' firft hygrometer was finiftied, I placed it in a cellar, the walls 
«nd gtoOnd of which Were wet^ and where it continued two 
months, without ever attaining its point of extreme moijiure. I 
have related that experiment in § 54. etfeq. of my firft Paper. 

30. When alfo 1 had the hygrofcopes mentioned above in 
the obfervations on dew^ I undertook a very long courfe of 
various forts of experiments on that important point of Ay- 

D 2 grology^ 



20 Mr. De Luc on 

grologyj of which however 1 (hall only give here the genera! 
and conftant refults, as furni(hed by thofe hygrofcopes. ** Tha 
•* maximum of evaporation in a mafs of inclofed air is far front 
** being identical with the maximum of moifture ; this being 
** dependent alfo, even to a very great degree, on the temper a^ 
** /2^r^ of the [pace J fuppofed to be the fame, or nearly fo, as that 
** of the water which evaporates in it. I^oifture may arrive to 
•• its extreme in an inclofed air^ if that common temperature 
^^ IS ncv^r freezing point ; but it becomes lefs and lefs, even to a 
" very dry ftate, as that temperature rifes, though the produSk 
" of evaporation^ thereby increafing, continues to be at its dif- 
** ferent maxima^ correfpondent to the different temperatures^* 
This is a very important propofition in bygrology ; which, from 
my experiments, would not be fubjedl to any objeftion, if thera 
were no other hygrofcopes than thofe I have mentioned above, of 
which I have thirteerj different fpecies ; but there is anorhen 
clafs of fuch inftruments, from which fome doubt might firft 
arife ; and I come now to that point. 

On two diflinSi clajfes of hygrofcopes. 

51. As I fliall now frequently fpeak oi flips and threads^ 
which conftitute thofe two clajfes of hygrofcopes^ I muft firft 
explain what I mean by thofe words. The Jlips compofe the 
clafs of hygrofcopes ufed in the above experiments ; they confift 
of very thin and narrow lamina cut acrofs the fibres of vege- 
table or animal fubftances, either in their natural or artificial 
breadths (as boards^^ or by reducing natural or artificial thia 
tubes of them into helices. By threads I mean the fame kinds 
of fubftances taken lengthwife^ either from their being natu- 
rally in thin threads, or by reducing them to that ftate» in 
3 tearing 



Hygromeiry. 21 

tearing from tbcm thii> fafciculi of ^hrei ; which operation is 
eafy in fome, as bempj wbalebonej and gut^ but very difficult ia 
others, as quill and fome forts of wood. 

32. The firft hygrofcopes of the clafs of threads^ which I 
obfcrved comparatively to the clafs oi Jlips^ were of bemf^^ gut^ 
wbalebone^ and fome woods^ and they exhibited a phsnome* 
non which at firft I could not underftand : when they were 
cxpofed with the Jlifis in damp air ; as, for inftancc, in open air 
during the fecond period of dew above determined, or in a 
glafs veflel inverted over water ; the /breads had only very 
fmall motions backwards and forwards round their point deter- 
mined in watery while thejlips had confiderable motions within 
that point, witho.ut coming near it, if the temperature was fen- 
i\h\y ?\>o\cJreezing point. Thence arifes the objeftion againft 
the general propofition above ftated : for thefe two clafles of 
hygrofcopes contradldling one another on the changes of moi/iure, 
nothing could be afl'erted in that refpedl, till there were fuffin 
cient reafons to exclude one of thofe claifes of informers, and 
to truft the other clafs, 

33. Proceeding to multiply the fpecies of thofe two clafles 
of hygrofcopes^ I found always the fame fundamental marcb in 
///x, all of them conftantly moving in the faoje direftion ; but 
in multiplying tlie fpecies of threads^ I found fuch variety 
between them, that in their own clafs they created diftruft ; 
fome of them, as of deal^ aloes pittu H^c^^ ^f H^^ tree^ quilU 
and iKinJlems of gramen^ in coming out of water ^ increafed in 
length ; they went farther that way, to a certain point, as the 
air was dryer : they retrograded then with accelerated fteps, 
when drynefs increafed, thereby returning to the point where 
they had flood in water ; and they continued to move in the 
fame retrograde way, with great acceleration, by a flill in*' 

creafing 



4 J Mr. ti£> Ltrc on 

creafing dryntfs. Moreover, they did not follow one iftothef 
in thofe motions contradidlory to the evident march of moijiure : 
each of them changed direftion at different periods, thereby 
often contradifting alfb each other, while the Jlips conflrantly 
agreed together in the direction of their motion, and alfo with 
all the other fymptoms of moijiure* From thefc comparative 
phaenomcna I firft concluded;^ that the motions of the fame 
kind, which I hadobferved in the firft- men tioned/iJrM^j, were 
alfo anomalies^ proceeding, only to a fmaller degree^from a caufe 
of the fame nature as that of thefe laft. After which, (imilaU 
fymptoms, which I had formerly ob/erved In the wj/^r thermo- 
meter near the freezing pointy made me firft conclude, from a 
general analogy ; that the perceivable modifications of the 
threads^ were the compound efFefts of two contrary operations 
of moijiure which followed different laws. 

34. Another phaenomenon led me foon after to a nrore de- 
termined theory in refpeft ' of thofe two oppofite effefts pf 
moijiure on threads^ I have faid above, that hemp and gut have 
only a very little retrogradaiion ; their greateft difference frona 
tht Jlips confifting in their being fiationary^ while the Jlips have 
ftill great motions* But when thefe fame threads are iwifled^ 
they acquire a very fenfible elongation beyond their point of 
extreme moijiure fucceeded by retrogradation-. From feveral 
trials 1 have made in twijling thefe threads more and more, I 
do not confider as impoflible, if fome difficulties, which I 
only could obviate in part, were completely prevented, that 
they might be brought to fuch a ftate^ as to have their point of 
extreme drynefs coincide with that of extreme moijiure ; by which 
means, in the progrefs of wo^^r^ from ont extreme to theotherj 
they would move firft in one direftion with decreafing fteps, thea 
ill the oppofite diredion by increafing fteps ; the whole, however, 

5 * vvith 



Hygrotnelry. 23 

tvith great *feg;uiirkies. Here then ^«^ fee two opfofite rffecls 
of m^ijiurii owe whkh Ungtbens the fibres i the other whtch^ 
by fwelling the twjled ftrings^ Jhortem them ; and we fee 
thofe effects follow, different laws^ from which is produced a 
retrogradatlon that we may change ad libitum. 

35. Now, the texture of Jinimal a«i<i VegetJible fibrous fub- 
ftances muft be a fort of reticle^ which exifts in thofe which 
are naturally in thin threads^ and in the moft minute fafciculi 
that we can feparate from a mafs ; and we fee it in the laft cafe, 
for in ftibdividing thofe fafciculi j there are always Jibres break- 
ing in tht points where they were anaftomofed with others ; 
confequiently, the primary Jibres of thofe fubftances form be- 
tween thetti mejhes fimilar to thofe of a net'i and thofe tnejhes^ 
which arfe 'widened by the introduction of water^ muft produce 
in the threads the fanae efFeft as the twijl in the 'zhcsvtjtrings. 

36. If thetl moifture^ in adling oi\ vegetable and animal 
ibreads^ natural and artificial, produces on their length two op- 
pofite effeSls ; one of which, fmall at firft but increafing gra- 
dually, compenfates at forti.e period the other which is firft 
vifible, and J^r/^^j it afterwards, fooner or later, according to 
the nature, of the tbreods^ il is evident, that they cannot be 
^oper for the, hygh^meter; fince, from the indication of fome 
of them it might fometinies be concluded, that moifiure 
changes in one fenfe, whfle it really changes in the contrary 
fenfe ; and from fome others, that moijiure is extreine^ long 
before it \& really ifo. As fot'the J?//>'j ; fince moijiure has only 
one effe^ on theit lengthy that of "widening more oi* lefs th^ 
mjhes of the crofs fibres ^ 1 ct>iicluded ; that all their hygrofcopic 
indications, hi every part of their fcale, were true in refpeft of 
increajezw^ decteafe oi moijiure \ and that confequently, thai 
clafs of hygrbjcopesxixv^x. be depended upon on that important 

point* 



24 Mr. De Luc on 

point. As for the exaft ratto between the indtcathm of thoCc 
laft hygrojcopes^ * and the changes of moijiurei that was to be the 
objeft of a particular inquiry, to which 1 now come. 



Of the fcalc of the hygrometer between the two fixed points* 

37. The long attention I had formerly given to the com pa* 
rative expanjions by heat of various kinds of liquids zw^folids^ 
made me expe£l the variety I afterwards found in the mo- 
difications of bygrofcopic fubftances by motfturei therefore, 
as I expreffed it in § 2. of my firft Paper, my view was only 
at that time, to find fome means of producing a fteady cempara* 
hie hygrometer ; but afterwards I pointed out, in §72,3 means 
which had occurred to me, for attempting to find the ratio be- 
tween the expanjions of fome determined bygrofcopic fubftance, 
and the correfpondent increafes of moifiure ; which was, to com^- 
pare the firft with the correfpondent changes of weighty of the 
fame or of any other fubftance ; an idea which I did not thea 
much fcrutinize, not yet thinking of its execution. 

38. From what I have faid above, I did not want any other 
motive of choice between the flips and the threads than tlieir 
comparative marches ; but though the flips agree always in the 
direSiion of their motions, there are differences in the progref- 
fion of their comparative fteps ; and that difference led me to 
examine more attentively the above means of finding which of 
thofe marches agreed beft with that of moifiure. The refult of 
that examination was diftruft, at leaft in refpe£l: of an imme- 
diate decifive means. With the view of rendering the changes 
of weight more eafily meafurable, I had firft thought of fome 
fubftance polTefled of a ftrong affinity with water ; but on con- 

fidcring. 



Hygrometry. aj 

filtering the hygrofcoptc phaenomena of thofe fubftances, it ap- 
peared to me, that their changes of weight could not be pro- ' 
portion al to the degrees of moijiure in the medium ; and that 
even the fenfe of the word moijiure applied to them was very 
difficult to determine (§ 14.). As for the fubftance of the 
hygrometer itfelf, I did not find any reafon to think, that its 
changes of weight could be more proportional to moijiure than 
its degrees of expan/ion; fincc on thefe laft depended in part 
the quantity of water that could be admitted into its pdres at 
each degree of moifiure in the air. 

39* Being thus difappoioted in my firft fcheme, I thought 
of a more diredt method, which was to zSt on moijiure itfelf, 
by firft producing, in a glafs veflel containing an hygrofcope^ as 
much drynefs as I could conceive poflible at that time, and 
then introducing into it fucceflive equal quantities of water ^ 
for which I had. found a fure means without opening the veilel. 
But then again fome previous experiments deflroyed my confi- 
dence in that method; having found, — ift. That the evapo- 
rated water had a tendency to depofit itfelf againfl the glafs 
by the fmalleft difference between the infide and outfide tem^ 
peratureSj even to the degree of becoming vifible on fome part 
of the veffel, long before I had any reafon to tyi^&, extreme 
moifiure, — id, That by the common temperature of my room, ' 
the hygrofcope in the veffel remained always at a confidierablc ' 
diftance from its point oi extreme moijiure^ though the bottom 
of the veffel was covered with water ; and that it varied with 
the temperature ; which could not have happened if moijiure 
had been ^extreme. — 3d, That when I endeavoured to increafe 
moijiure in the veflel by cooling it, 1 produced very often the 
contrary effed, at the fame time that a quantity of the diffemi- 
nated water gathered over the glafs. 

*VoL.LXXXI. E 40. As 



2(5 Mr. DE Luc on 

40. As in thofe trials the contradidion between the marches 
of the Jllps and the threads was very evident, I was >the more 
difappointed to find, that the uncertainty of the re^l degrees 
of moifture increafed at that very f)eriod : for inftance, fetting 
out from fome dry point, and moifture increafing, the march of 
a thread of whalebone was evidently in a decreajing prc^reffion^ 
comparatively to that of zjlip of the fame fubftance i and whea 
at laft there was a fuperfluous quantity of water in the vefiel, 
and the temperature was made to change, the thread was 
almofl Jlaitonary^ while the Jlip had confiderable motions^ 
often contrary to the fmall motipns of the other ; while it was 
at that very period, that the real degrees of moifture in the 
veiTel could not have been afcertained but by' an already fettkd 
hygrometer. I had no doubt that thofe anomalies were to be 
attributed to the thre/id of whalebone^ not only becauie of the 
excefs of the fame modification in other threads ; but alfo con- 
fidering the analogy between the comparative marches of tke 
two kinds of hygrojcopes^ and thofe of the thermometer Sf of 
water and guickfi/ver : but as this was a very important ob- 
je£t for natural philofopl^^ I would not decide it from thofe 
firft appearances ; and that confideration led me to a very great 
iiumber of various forts of experiments, which I made in view 
of multiplying at leaft the ipdire^ fa£t$ with whicl;^ my theory 
might be compared. However, as at laft I found a more dire£b 
means of verification, I ihall only mention that, laft clafs of 
experiments* 



Expe^ 



Uygrometry^ %j 

Experiments on the comparative changes »f weight and dimcn* 
iions of fome hygrofeopic fubftances. 

41. I have faid above, that I could not find any folld reafoa 
to confider the changes in weight of a fubftance, as being 
more proportional, than its changes in dimenjions^ to the cor- 
refpondent changes of moifiure in the medium ; which doubt had 
prevented me from undertaking that courfe of experiments. 
But it occurred to me at laft, that if my theory on the compa- 
rative marches of the flips and the threads were true, it might 
be rendered certain by comparing thofe marches with the increafe 
oi weight of the fame fubftance : for inftance, taking ?ijlip and 
a thread of deal^ and having fome deal hung to a fcale, I was to 
find, that while iht Jlip continues to lengthen, and the thread 
to (horten, the fubftances continue to receive watery and, 
in general, that the march oi Jltps^ in every part of their fcale 
on which the experiment may be regular, was more proportional, 
than that of threads^ to the correfpondent changes in weight of 
every bygrofcopic {xkh^znct of the elajlic kind. 

42. This having ftruck me as a fure means of deciding the 
queftion, I fet immediately to work; and (ince that time I 
have made a great number of experiments of that kind. They 
were not at firft very accurate ; but fucceflively I have mended 
both the inftruments and the apparatus; and, after having fettled 
every part that I looked upon as eiTential, and made in confe* 
quence a new apparatus and new inftruments, I have begun a 
regular courfe of experiments, of which I (hall give here the 
firft refults. 

43. The apparatus coniifts in two, tin veffelsrthe firft of 
which, and the moft ufed, is i6i inches high, 15! wide, and 
5 deep. The front of this veffel is a plate of glafs, and the 
back a tin-platc^/V^rr, which, being taken off, leaves that fide 

E 2 of 



28 Mr. DE Loc on 

of the veffel quite open. The fecond veflel has the fame di- 
menfions as the firfl; but its back is foldered, and its front ie 
of woven brafs wire. This veflel may be applied to the back 
of the former, in fuch manner as to make of both one fingle 
veflel, which, when the Jllder of the fore-part is taken off, is 
only divided by a vertical partition of woven brafs wire. The 
ufe of that fecond veflel is to produce extreme drynefs in the 
other ; for which purpofe it is filled with large pieces oi quicks 
lime taken from the kiln. When that veflel is not \ifed, it is kept 
in a tin box which it fills intirely ; and when it is in, as well as 
while it is out for ufe, that box is kept fliut with putty, by 
which means the fame lime may ferve many times in the fol- 
lowing manner. 

44. When I want to produce extreme drynefs in the firft 
veflel, I apply ^o it the fecond, fattened with hooks ; I then 
pull out thj&Jlider of the firfl:, and ftop with putty the chinka 
between them. When that firfl: operation is completed, I pu6 
again xYitJlider to the fore-velfel, and take off" the other. Ill' 
this lafl operation, fome moifiure might be introduced through 
the chinks of the flid^r, before they are again fl:opped with putty ; 
efpecially as the deflruflion of moifture in the veflel has made 
room for more air to come in ; but I prevent it by making firfl: 
the apparatus fenfibly warmer than it was when I put on the- 
lime-veflel ; by which means, in the little time employed for. 
the operation, the motion of the air is from the iufide to> 
the outfide, which prevents all accefs of moifiure in the veflel. 

45* To that firfl: operation fucceeds that of a gradual -intro* 
dudtion of moifture into the apparatus. It would have been 
lafelefs to apply to that procefs the means I had imagined, fpr 
fpreading fucceflive equal quantities of water in a clofq veflel ;: 
for the evaporated water depofiting itfelf in part, more or lefs^ 
on every furface, and the furfaces, efpecially of gfafs^ being, 

\ very 



Hygrometry. 09 

rery much muhiplied in that apparatus when filled With in- 
ftruments, no real correfpondence could be expe£ted between 
the quantity of evaporated water and the motion of the 
inftruments; therefore I again gave up the view of determining 
that ratio^ and proceeded in the following manner. At the 
bottom of the apparatus, on one of its fides, there is an open- 
ing, I an inch high, and 2| inches broad, which ufually is 
kept (hut with a tin plate and putty. The taking off, only 
for a moment, that tin plate, is the firft operation by which I 
introduce mcifture into the apparatus ; which being then reduced 
to the temperature at which I make all my obfervations, namely, 
60® of Fahrenheit, permits the external air to enter the veflel, 
and come to an equilibrium with it at the fame temperature. By 
keeping off the tin plate longer and longer, I admit new quan- 
tities of moijlure into the veffel ; and when that means is become 
iuefl[edual, I introduce through the fame opening, a brafs 
frame, which extehds under all the inftruments, on which is 
ftretched a cloth that I wet hj degrees more and more, as long 
as it may produce fome effe^ at the above temperature. In 
order to have that temperature when I want it, I make thofe 
experiments in a feafon when I may have fire in a flove at a 
proper diflance from the apparatus. The time when that 
equal temperature is neceffary in many refpefts, is that of the 
obfervations, which I make twelve hours after each new intro- 
dudion of moijlure. 

46. The indruments I place in that'apparatus are of two kinds ; 
the firft of which are beamsy made on the principle ufed by Mr. 
John Coventry in \i\% paper hygrometer^ which principle I have 
found of great ufe ; for, with beams of that fort, as delicate as 
mine are, if the total change of weight in an experiment is 
not above i grain, ^^Vv P^*^ ^^ ^* ™^y ^ diflinftly obfervcd 
on a weight from 3 or 4 to so grains ; but in my experiments, 
3 iu 



go HJr. DE Luc on 

in which the total variation was from 5 to 6 grains, the ob- 
fervable part was only ^^^ part of a grain. Thcfe two beams 
are placed on the fame line through the middle of the depth of 
the veffel, and their indices move in that plane ; their motions 
are in an oppofite fenfc by the fame changes of weight, be- 
caufe I wanted the two fubftances fufpended to the beams^ to 
hang near one another in the middle of the veflel. The other 
inftruments are frames^ in which an index is mbved by the 
variations in length of a very thin flip or thread, Thefe frames 
are placed before and behind the beams. 

47. In the firft experiment that I made with that appa- 
ratus, the fubftances fufpended to the beams were deal and 
quilK reduced to very thin Jbavings^ which were ftretched 
edgewile in thin brafs-wire frames. The weight of each kind 
i)f x}[vti^ Jhavings was 1 2 grains, at a certain degree of the ther- 
mometer and of my hygrometer. The other hygrofcopes were 
flips and threads of the fame fubftances as the Jhavings^ and 
• alfo of whalebone. Thefe fix laft inftruments have their point 
<yi extreme drynefs taken in my lime-vejfel^ and their point of ex^ 
treme moifture m water \ the interval between thefe points is 
<livided into ico parts ; and on the fcales of the threads the 
degrees are prolonged beyond this laft point. The hygrofcopic 
fcale of the Jhavings could not be fixed before the operation ; 
therefore the fcales of the beams ferved only to indicate the 
comparative motions of the index ; but afterwards, taking for 
o, the point where the index ftood by extreme drynefs^ and for 
100, the point o( extreme mo j/luref which I fhall explain, the 
interval between thefe two points became a modulum by which 
I have alfo reduced into 100 parts of the whole the changes 
obferved in the weight of the Jhavings. I (hall not give here 
the abfolute quantities, either of the changes of weighty or 

of 



HygromHry.. ^r 

of thofe in length of the other bygrofcopes^ having not had 
time to make the neceflary calculations, of which however I 
have the daU. 

48. The neceffary time for a complete difFufion of the newly 
introduced moifture in the vefTel renders it impoflible to proceed, 
in that introdudtion, by regular fteps. The method I ufe is, 
to obferve the motion of my ufual hygrometer^ which is Tijlip^of 
whalebone^ and to remove the caufe of increafe of moi/iure be- 
fore it has moved 5 degrees. In that manner the fteps of the 
increafing moifture have been in general lefs than 5 degrees of 
that inftrument; but, by interpolation, I have reduced them 
to what they would have been if the fame inftrument had 
been moved fucceffively 5 degrees. 

49. I have faid before, that when the maximum of evapora* 
tm is produced in a clofe veffel by a temperature fenfibly 
above the freezing pointy there is no regularity to be expcdled in 
any farther attempt to increafe moifture \ the difleminatedi 
water being then abundant, the fmalleft difference of tempe- 
rature between difierent parts of the apparatus makes it depofit 
itfelf on fome furface, and pafs from one to the other (§39*) ; 
which circumftance is alfo mentioned by ProfeiTor Pictet of 
Geneva, in his late work, Effais de Phyfique. For that rea- 
foD, when the evaporated water in the veilel was near its maxi^ 
mum^ my laft operation was, to put in again the wet clothe while 
I kept the temperature at 60°, and to take it out when the indices 
of the beams were fixed. My ufual hygrometer was then at 
87^; and as It had ftill 13 degrees to move towards its point of 
extreme moifture^ and all the others in proportion of their known- 
marches^ I have added to the obferved increafes of weight in 
the Jbavings^ a quantity proportional to their former marches 

2 comparatively. 



3* Mr. DE Luc OH 

comparatively to that of their refpe£tive ^/)>j ; and tlius arc 
completed their bygrofcopic Jbales. Repeated trials have ihewn 
me, that the weight of the JJjavings increafes as long as their 
flips iucreafe in length ; but as there is no regularity in their 
comparative marches at that period of moijiure in a veflel, nor any 
poflibility of making thefe experiments in open air, becaufe of 
the beams ; the addition mentioned^ which forms the three lad: 
terms of the columns of t\it Jbavings in the following table, is 
to be coniidered only as having determined the modulum of the 
Qbferved terms ; fince it has not changed the ratio between them, 
nor confequently the correfpondeht marches of weight and 
length fo far ; which were the only ohjeSt of the experiment. 

50. Before I come to the general refult of that experiment^ 
I (hall place here a comparative view of the two kinds of phe- 
nomena, which, by their analogy, led me firft to the theory T 
have expofed : I mean the comparative marches of the Jlip and 
thread of whalebone on one fide, and thofe of the thermofcopes 
of quickfiher and water on the other fide. In this table the 
correfpondent terms of the hygrofcopes^ from o of both to 85 of 
the Jlip ^ have been obferved in the above experiment ; the four 
following are the refults of obfervations in time of increafing 
dew. The correfpondent terms of the thermofcopes are deduced 
from the table of their comparative expanfions which I have 
given in § 418. w. of my work, Rech.Jur les Mod. de VAtmo^ 
fphere\ from which table this only differs, ift, by a change 
of the modulum^ in the ratio of 80 to 100; 2d, by an inver^ 
Jion^ which brings the terms of this table to exprefs compara- 
tive condenfations of the two liquids. 



HVGRO- 



Mygromttry, 



B3 





Hyoeoscopbs. 


Thbrmoscopbs. 


Whakbone Whalebone 


Qjiickfilver. 


Water.^ 


' 


Slip. Thread. 






Extreme 


o 0,0 drynefs. 


Boiling 


0,0 ^0I»/. 




5 »*,' 


5 


9»3 




10 30,1 


TO 


18,3 




15 41,1 


"5 


26,3 




20 51,1 


20 


35.0 




25 5%^ 


*5 


4»,7 


• 


30 65,6 


30 • 


49»2 




35 71,1 


35 


56,7 




40 7<5,5 


40 


63, f 




45 8i,« 


45 


69,0 




50 85^,8 


50 


74,5 




55 88,8 


55 


79>« 


- 


60 91,3 


«o 


83,8 




<5 93,3 


65 


87.9 




70 95,6 


70 


91.^ 




75 97,6 


75 


^5.o- 


! 


80 98,6 


«o 


97.5 


• 


85 99,6 


• •• :85 ' 


98,9 




90 106,1 


• 90 , • 


99.9 




95 100,5 


<^^1 . 


100,5 


Extreme 


100 100. motfture. 


Freezing 100 


100. point* 



51. The firft part of that table fhews, the great fteps of the 
ibrtad of wbalebme^ comparatively with thofe of iht Jlip of the 
fame fubftance^ at the beginning of their correfpondent increafe 
in length ; but the thread relents by degrees^ and a nearly Jla^ 
tionary ftate fucceeds, in which, while this bygrofcope moves 
firft 1,9 degree from 9896 to 100,59 then retrogrades 0,5 

VoL.LXXXI. F degret 



|4 Mf^ DA Lira on 

dtgree to come to its point of extreme moijiure ; the Jlip^ con- 
tin ding to molrc irt the former direction, goes over 2d degrees. 
The phaenbmena are the fame in the part of the table relating 
to the tbermofcopesy that of water proceeds alfo at firft by great 
ileps, conjparativcly to that oiquickfilver ; after which it relents ^ 
and while it moves, only 3 degrees, and retrogrades o^s degree 
to come to t\it freezing point ^ the quickfilver one, continuing to 
move in the fame dire£lion, goes over 20 degrees. It was 
from that phenomenon of the water tJurmoJcope that I con- 
cluded formerly, that there was in its march a Jlationary ftate, 
during which the beat decreafed nearly as indicated by the 
quick/ilver ont I and that conclufion was afterwards confirmed 
by direft experiments. From that afcertained. faft, I was led 
to conclude, with refpeft to moifture^ that there was alfo a 
Jlationary ftate in the march of hygrolcopic threads^ even ia 
thofe which had the fmalleft retrogradation^ as that of wbale^ 
lone; and this theory will be confirmed by the refults of the 
above-defcribed experiment. 

52. The following table contains th(^e refults, namely, the 
correfpondent marches of all the mentioned hygrojcopes; the 
Jbavings increaiing in weighty and xhtjlips and threads in lengths 
The 3 laft comparative terms do not refult fiom that particular 
experim/ent ; for ; the pavings (as I have faid above) they are 
coiKluded from the, former comparative fteps ; for the other ivt- 
ftruments, they have been obtained by obferyations in the 
o|>en datt^ air« 



Wbalb- 



Hygromttry. , 35 



Whalsbokb. 


QvihU 




Dbal. 




SUp. 


Thread. 


Shaving!. Slip. Thread. 


Sbwiag^ Slip. 


Thr. 


Sstr. drya. o 


0,0 


0,0 


0.0 0,0 


0,0 


«,o 


0,(^ 


5 


12,1 


7.0 


4.8 40,0 


6.2 


5.4 


4».o 


10 


30.* 


^1,0 


9.7 . 72.0 


9.4 


ii,t 


69.4 


«5 


41.1 


20,0 


14.4 85.0 


15,6 


«6,5 


94,8 


9Q 


5«.« 


!|6,0 


«9.» ^5»^ 


»a.6 


21,9 \ 


107,0 


a5 


59. » 


3».o 


23.9 101,0 


47,0 


«;»» 


«I3»6 


30 


65,6 


36,0 


28,5 105,0 


33.* 


3a.7 


ti8,6 


35 


7i.» 


42.0 


33.3 '07.0 


36.0 


38,3 1 


(22,6 


40 


76,5 


43.8 


38,3 102,0 


4r.a 


43.7 


(20,6 


4$ 


81.S 


48,3 


49,9 104.0 


46,7 


49.3 I 


t*3A 


50 


85,8 


52.3 


47,4 107,0 


49.7 


54»6 1 


ra6,6 


55 


88,8 


56.5 


52,4 103,0 


56. « 


59.9 1 


i»9.7 


60 


91.3 


60,5 


56,9 105,0 


S9.9 


64,9 


122,7 


6S 


93,3 


64.4 


61,9 106,0 


63.7 


69.7 


««9.V 


70 


95.6 


69.4 


67,2 xo8,o 


67.1 


74.5 1 


ri7,6 


75 


97.« 


74.0 


7«,« 107,0 


73»4 


79.0 ' 


'«5.6 


80 


98,6 


78,0 


77,8 106,0 


78.* 


83,5 1 


iia»^ 


?5 


99.6 


84.0 


8«,8 105,0 


83.8 


87.S ' 


t>o,p 


90 


100,1 


« 88,0 


88,2" 1036 


••88,8 


92,0 1 


07,0 


95 


ioo,s 


♦ 94.0 


94,0 102,0 


•93.8 


96,0 1 


03.6 


fixtr. moift. too 


100. 


•100. 


too. too. 


♦loa 


100. 1 


00. 



From the 18 firft termi of that table^ which are the imme* 
diate refuks of the experiment, we are now to examine my 
opiuioq, that the lengthtnif^ pf xht flips of wbaltb§ne^ quill^ 
and ^^K beyond tbefe terms \» a fure figo that^ till they have 
attained thetr pcHnt lOOj mo^wrt continues to increafe in the 
medism where they are placed^ 

i(3. There €9uld not beany doubt on that propc^tion, if it 
were not for fome threads Similar to that of wbakkme ; which 
threads^ having (enfibly attained their utmoft Ungtb at tb^ 
period when the experiment was Aopped^ feem to wdiratct that 

F a moifture 



:j6 Mr.j>vLvc'on 

fnoijlure is then at its maximum. But if the lengthening of 
hygrojcopic threads in general^ is the compound effeft of two 
oppoCte caufes which follow different laws'; it may be that^ 
In fome threads, thole caufes happen to conipenfate each other 
at that very period ; by which means they zttftationary^ though 
moijiure continues to increafe. This was my opinion, and the 
above experiments were undertaken to verify it, firft, by com- 
paring the march of the Jlips with the increafe in weight of their 
own fubftance; fecondly, by compearing the /w^^rrA^i of different 
kinds of threads with each other, and alfo with the increafe in 
weight of their fubftance : and from that now we are to exa- 
mine the above propofition. 

54. In refpeft of the Jlips my theory is, that as moifture 
cannot aft on their length but by widening the mejbes of their 
tranfverfal fibres^ they cannot go ox\ lengthening but by im- 
bibing more and more moifture^ from its increafe in the air ; 
and this we fee to be the cafe, by comparing the marches of 
the three kinds oi Jlips with the correfpondent increafes in 
nveight of the quill znA deal (havings, during the whole pro- 
grefs of the experiments There are difierences in t\io(t marches 
as I expefted (§ ^y^ ; but they are not fuch as to give the 
fmalleft ireafon to fufped, that afterwards, during the period 
of the three laft terms of the table, in which we have no cor- 
refpondent obfervations of increafes of weight in the Jbavingt 
of deal and quill^ the fame law does not take place as in the 
17 antecedent terms. If the experiment was only made with 
one kind of Jlipj it might be objefted, that though that JUp 
lengthens regularly during the whole increafe of moifture from 
its minimum to its fuppofed maximum j it is not impoflible but 
that immediately after, by fbme peculiarity of its nature, it 
will lengthen^ without any farther increafe of moifture in the 

medium. 



' Hygromalfy. ^y 

nudttim. But that formife cannot be admitted when xhtjlips of 
fuch diffimilar fubiknccs as w^ii/?^M^, quil!^ znd deal^ fenlibly 
agree in their motions at that period^ and when a number of other 
Jlips of the vegetable and animal kinds follqw alfo the fame 
general march. 

§S* In refpeft of the threads^ which are the only caufe of 
the above doubt, mv theory, which removes it, is alfo con* 
firmed by that experiment. That caufe of doubt is exemplified 
in the table by the thread of whalebone^ which has almofl no 
motion^ while its Jlip moves from 85 to 100. At that period 
of moifture^ no r^ularity can be expeded from experiments 
made in clofe veffels ; by which circumftance, not having the 
correfpondent obfervations of weights^ it cannot be demon- 
ftrated by immediate experiments, that the thread of whale^ 
bone is then ftationary from its nature ; but the threads of 
quill and deah which are in that ftate during the regular courfe 
of the experiment, will guide us in that enquiry. The thread 
of quill h Jlatiofiary during that great part of the obferved in-» 
creafe of moijture^ by which the thread of whalebone moves 
from 71 to 97»6: the thread of deal is alfo ftationary^ while 
the fame /i^rM^ moves from 71 to 91,3. They both after- 
wards retrograde i the quill from 107 to 100, and the deal 
from 122,6 alfo to 100 ; and it is during the latter part of that 
retrogradation^ correfpondent to a continued direSl motion of 
the Jlips^ that the thread of whalebone^ and fome more of its 
clafs, after a very decreafing march comparatively with all the 
flips^ are at hRjSationary^ and then a little retrograde. In that 
ftationary flate of the threads^ while moiflure proceeds in the 
fame diredbn, they move backwards and forwards, more or 
lefs, according to the duration of that flate, and to the quan-^ 
tity of the retrogradation. This may be fcen by the table, iu 
< :. refpeft 



38 Mr. DS Luc on 

refpe^D: of the thread oi deal and quiili aad I have obferved k 
conAantly^ in a foialler proportion, in aM the ibreads which 
have their Jlaiionary ftate at the laft period of ma^n^ with 
this particular circumftance in all tho(e motions backwards and 
forwards, that they are never the fame in two different experi** 
ments. That fymptom already points out a complication of 
caufes ; but we (hall foon fee a more diftinft proof of their 
exifterice* 

56. My theory on the march of hygrofcopic threads it 
founded on this general principle, that a retrograde effe£l, how 
fmall foever it may be, if it is not produced ^y a correfpon^^ 
dent change in the caufe itfelf, is preceded by zjiatumary ilate^ 
during which^ and the retrogradatim^ the inteniity of thtf 
caufe continues to increafe: and this alio is exemplified in the 
experiment. The Jiationary ftate of the thread of deal begins, 
when its Jhavings have only imbibed from the air a quantity 
of water = 36 ; it is flill at the fame point when the quantity of 
imbibed water has increaied to 59*9 ; and in the part of its 
retrogradation^ which is ftili contained in the regular courie of 
the experiment, that quantity of imbibed water increales to 
88,8. The fan^, with only fome differences in the degree, is 
feen in the thread of quill \ therefore, as we fee alfo fbme^ 
though a very fmall, retrogradatidn in the thread of wbaleAone^ 
as well as in other threads of the fame clajsf we have reafon to 
conclude, that their apparent immobility before they come to 
that point, while thtjlips continue to move, is alio z Jiationary 
ftate, during which they continue to receive water, by the 
increafe of moijiure in the air. 

57* The experiments I have now analyied are only one iet 

amongil others which, though made with lefs accuracy^ have 

given the i^me general refults. ^ Theftt reUting to various 

I kindf 



Hygrometry\ ^^ 

kinds of fubftances, I intend to repeat, and to have the honour 
of comnnuniclating their refults to the Royal Society ; and I 
ibail conclude this Paper, with an immediate demonOration, 
that the hygrofcopic naotions of the Jlips are iimple, while thofe 
of the threads are the combined eiFe£ls of two oppofite caufes : 
which will be a further confirmation of the whole of .the 
above theory. 

On the recolr of hygrofcopic threads. 

58. When formerly L concluded from the phenomena of 
the water thermojcope^ that its. cqndenfati&ns were the combined 
efiefits of two oppofite caufes, which fbllow^ed different laws^ 
it was not for having diftingQi(hed thofe two efieds ; hut only 
becaufe of ;^fmall retrogradation near thcjreezmgpohty preceded 
by Vk^tknary (late, comparatively with the march of quickfil'oer ; 
but in the cafe of hygroicopic threads and Jlips^ in which We 
have the fame phasnomenon^ the two oppofite efl^As are diflin- 
guifliable in the threads^ by <Mie being operated more rapidly 
th^ the other. If, for indance, I tranfport from a drier to a 
damper place (or inverfely) the two kinds of quill hygrofcopes, 
xhtjlip proceeds in an even courfe to a certain point, where it 
remains ^^^; but the thread moves in an interrupted mznutt 
al(b to a certain point, whence it recoils. If that experiment 
is made within the limits of the ftationary ftate of the thready 
it may recoil as much as it has gone the other way, and be 
fixed at the fame point in both places. The cafe of thtjlip of 
^U is coaunou to evtryjlipj and that of its thread to all others 
which have a quick motion. Here then we hzvefeparatefy thetwo 
e&ds of tnoijture on the threads ; that on thejfibres themfelves 
is the/oom^ produced^* and at firfl predominates : the Jowf/l, 

by 



40 Mr. Dft Luc on 

by which afterwards the firft produced is more or lefs com^ 
fen/ate Jj is that operated on the width of the mejhes ; and it is 
becaufe the laft of thofe effcfts is the only one that can afFeft 
the length of the Jlips^ that, in every change of fn$ijurey they 
move evenly^ without any recoil. 

5 9^ To that demonftration of the exiftencc of two oppofite 
effe^s of moifture in the threads^ I (hall now only add an exam^ 
ple of a fimllar phenomenon, in which the caufes alfo are 
vifible. The compound frames^ mentioned in § 24. are formed 
of two glafs rods 4 feet long, iixed together at the bottom and 
the top. A thin flip of brafs of determined length, fixed to 
one of the glafs rods towards the top, comes down from thence, 
pafles over a pulley at the bottom, and turns up for half an 
inch. To this end of the irajs flip is fixed the lower end of 
the hygrofcopic fubftance, the upper end of which is connefted 
with the index of the infl:rument. It is by that means that, 
whatever be the changes of beat^ provided they zttJloWf the 
lower end of the hygrofcopic fubftance remains fenfibly at the 
fame diftance from the axis* But if I take that infl:rument out 
of water at a lovf temperature^ and plunge it immediately into 
warmer water, the index infl:antly moves as if the hygrofcopic 
fubftance had lengthened ; which is the effeSl of the brafs flip 
dilating fooner than the glafs rods ; then the index recoils^ and 
this is the effeSl of zjlower dilatation of the glafs. 

Conclufton^ * 

60. 1 have concentrated in thefe pages an account of twenty 
years afliduous labour in hygrometry^ moftly occafioned by the 
anomalies of the hygrofcopic threads i and the principal refults 
have been, fome determinations of the four ^principles that 

directed 



^irefted mc from the begtnning, wliich now are a$ follows 
ift, F/W, as caufe of beat^ is a fure, aud the oiily fure, ipeaqs 
of abtaiiimg e^trtt»i drynefs: this is produced by white h^at in 
every bygrojcopk fabftance that can bear it ; and it may be thus 
tranfmitted to t\\^ hygrometer, 2d, Water ^ in its liquid ftatc, 
is a fure, and the only furp, means of determining the point of , 
extreme molfiure on that inftrument. 3d, It is not to beexpeded, 
^ priori^ of any hygrojcafic fubftance, that its changes be pro- 
portional to thofe of tnoifiure ; but it may be affirmed, that 
nojibrous or vafcular fubftance, taken lengthwifey is proper for 
the hygrometer^ 4th, A means of throwing light on the march 
of a chofen hygrometer^ may be, to compare it with the cor- 
refpondent changes in weight of many hygrofcopic fubftances, 

6i. From thofe determinations in hygrometry fome great 
points are already attained in hygrologyy meteorology^ and che-^ 
mijtry^ of which I (hall only indicate the moff important, ift. 
In the phasnomenon of dew^ the gr^fs often begins to be wet 
when the 4/r, a little above it, is ftill in a middle ftate of 
moifturei and extreme moiflure is only certain in that air^ when 
every folid expofed to it is wet (§ 28.). 2d, The maximum of 
evaporation in a clofe fpace, is far from identical with the maxi'- 
mum of moifture ; this depending confiderably, though with the 
conftant exiftence of the other, on the temperature common to 
xh^ fpace and to the water that evaporates (§ 30.). 3d, The 
cafe of extreme tnoifiure exifting in the open tranfparent air, in 
the day, even in time of rain^ is extremely rare : I have ob- 
ferved it only once, the temperature being yf. 4th, The air 
is dryer and dryer as we afcend in the atmofp^ere ; fo that in 
the upper attainable regions, it is conftantly very dry^ except in 
the clouds. This is a faft certified by M. de Saussure*s ob- 
fervations and mine, fth. If the whole atmofphere pafied 

Vol. LXXXI. G from 



42 Mr. DE Luc m Hygrometry. 

from extreme drynefs to extreme moijiure^ the quantity of water 
thus eiiaporated would not raife the barometer as much as half 
an inch. 6th, Laftly, in chemical operations on airsy the 
greateft quantity of evaporated water that may be fuppofed In 
them at the common temperature of the atmofphere, even if 
they were at extreme moijiure^ is not fo much as -^^ part of 
their mafs. Thefe two laft very important propolitions, have 
been demonflrated by M. de Saussure. 






PhiloM, Tra,it. Vol. LHH. Tab. L p. 4i. 




[ « ] 



II. On the Produdion of Ambergris. A Communication from the 
Committee of Council appointed for the Confideration of all Mat- 
ters relating to Tr^de and Foreign Plantations ; with a prefatory 
Letter from William Fawkener, Efq. to Sir Jofeph Banks^ 
Bart. P. R. S. 



Read January 20, 179U 

TO SIR JOSEPH BANKS, BART. 

Office of Committee of Privy Council for 
Trade, Whitehall, 15th January, 1791. 

SIR, 

LORD Hawk£sbury, Prefident of the Committee of Privy 
Council appointed for the Confideration of all Matters 
relating to Trade and Foreign Plantations, having received a 
Letter from Mr. Champion, a principal Merchant concerned 
in the Southern Whale Fifhery, informing him, that a (hip 
belonging to him had lately arrived from the faid fifliery, 
which had brought home 362 ounces of ambergris, found by Mr* 
Coffin, captain of the faid fhip, in the body of a female fper- 
maceti whale, taken on the Coaft of Guinea ; his Lordfliip 
thought fit to defire Captain Coffin, as well as Mr. Cham- 
pion, to attend the Lords of the Committee, that they might 
be examined concerning all the circumftances of the faft before 
mentioned ; and I am directed by their Lordfliips to tranfmit 

G 2 to 



J 



44 OntSerPrtfiu^icnof 

to you a copy of the examination of thefe two gentlemeny 
that you may communicate the fame to the Royal Society, if 
you (hould think that any of the circumftanees, ftated in this^ 
examination, wiU contribute to remove the doubta hitherto 
entertained concerning the natural hiftory and produftion of 
this valuable drug. I fend you alfo a piece of the ambergris 
fo taken out of the whale, and fonde of the bills of the fiih^ 
called Squids (which are fuppofed to be the food of fperma- 
eeti whales), and which were found partly in the ambergris 
taken from this female whale, and partly on the outfide of it^ 
and adhering to it. 

I have the honour to be, &c.' 

W. FA WKENEK.. 



At the Council' Chamber, Whitehall, the 12th January, 1791^ 

By the right honourable the Lords of the Com* 
xnittee of Council appointed for the Confidera* 
tion of all Matters relating to Trade and Fo^ 
reign Plantations. 

READ — ^Letter from Mr. Alexander Champion, a prin- 
cipal merchant concerned in the Southern Whale Fifliery, to 
Lord Hawkesburt, dated the 2d inftant, acquainting his 
Lordfliip, that Captain Joshua Coffin, of the fhip The 
Lord Hawkeibury, is lately arrived from the Southern Whale 
Fifliery ; and that the (aid fhip, befides a cargo of y6 tons of 
fpemaceti oil and head-matter, has brought home about j6o 

ounces 



Amiergrh. ^-j- 

nances of ambergris, which the faid captain took out of the 
body of a female fpermaceti whale ou the Coafl: of Guinea. 

Meffi Champion andGJoppiN attending, were then called 
in, and the following queilions were put to Mr* 
Coffin, vi%. 
Q, Have any of the whales, taken before by (hips failing from 
Great- Britain, to your knowledge, contained any ambergris ? 

A. None, that ever I heard of. The American fliips have, 
at times, found fome. 

Q. Was the ambergris, found by you, in a bull or cow 

A. It was found in a cow fifli. 

Q. Is it ufual to look for ambergris in whales that are 
kiUed ? 

A. It has not hitherto been much the practice to do fo. 

Q. How happened it that you di£:overed this I 

A. We law it come out of the fundament of the whale ; 
as we were cutting the blubber, a piece of it fwam upon the 
furface of the lea. 

Q« In what part of the whale did you find the remainder I 

A. Some more was in the fame paiTage, and the reft was 
contained in a bag a little below the paflage, and communi- 
cating with it. 

Q. Did the whale appear to be in health ?* 

A« No ; (he did not* She feemed fickly, had no flefli upon 
her bones, and was very old, as appears by the teeth, two of 
which I have. Though (he was about thirty-five feet long, 
(he did not produce above one ton and a half of oil. A fi(h of 
the fame fize, in good healthy would have produced two tons 
and a half. 

Q. 



46 On the ProduSlion of 

Q. Have you obfervcd the food that whales generally feed 
upon ? 

A, The fpermaceti whale feeds, as I believe, almoft wholly 
upon a fi(h called Squids. I have often feen a whale, 
when dying, bring up a quantity of fquid, fometimes whole, 
and fometimes pieces of it. The bills of the fquid (fome of 
which Mr. Coffin produced) were found, fome in ,the infide, 
and fome on the outfide of the ambergris, flicking to it. 

Q. Did you ever find any ambergris floating on the fea ? 

A. I never did, but others frequently have. 

Q. How long have you been engaged in the whale fifliery ? 

A. It is about fixteen years fince I firfl entered into it. 

Q. What is the general proportion of bull and cow whales 
you have met with ? 

A. I believe the proportion to be nearly equal. In my \zSt 
voyage, however, I found only four bulls out of thirty-five 
whales. I fifhed upon the Coafl of Africa between five North, 
and feven South degrees of Latitude. I am inclined to think, 
that the cow whale goes to calve in the low latitudes, which 
accounts for more cows being found in thofe latitudes. 

Q. Is there any particular feafon when the cow whales 
calve ? 

A. I do not know that there is. 

Q. Does the bull or cow whale, in proportion to their fize, 
produce mofl oil ? 

A. The cow whale, when big with calf, produces more oil 
than a bull whale of the fame fize ; when fuckling, (he pro* 
duces lefs. 

Qj^Are the whales ufually found fingly, or in pairs ? or ia 
larger numbers ? 

4 A. 



Amhergris^ 47 

A. Ufually in large numbers, which we call Scools, and 
particularly in the low latitudes. I have feen from fifteen to 
perhaps a thoufand together. 

Q^ Have you any further information on this fubjeft to 
give the Committee ? 

A. We have generally obferved, that the fpermaceti whale, 
when ftruck, voids her excrement ; if (he does not, we con- 
je£lure that fhe has ambergris in her. I think ambergris moft 
likely to be found in a fickly fi(h ; for I confider it to be the 
caufe or the eSe£t of fome diforder. 



Queftions put to Mr. Champion* 

Q. At what price does ambergris ufually fell ; and at what 
price did that, taken by your (hip, fell ? 

A.. A fmall quantity had lately fold at z^s.per ounce; but 
it was then very fcarce. Mine fold for 19J. 9 //./^r ounce. 
The whole quantity, found in this whale, was 362 ounces 
Troy. The people who bought it told me, this was a larger 
quantity than was ever before brought at once to market. It 
has been generally fold at about 4 or 5 pounds at a time. 

Q. For the ufe of what country was this ambergris bought ? 

A. I do not exaftly know. It was bought by a broker, 
who told me, that his principal, who purchafed about one 
half, bought it for exportation to Turkey, Germany, and 
France. The other half was purchafed by the druggifts in 
town* 



"m^ 



[ 48 ] 



III. Obfervations on the 4lJ^nUy betwien Bafaltes and Granite, 
By Thomas Beddoes, M. -D. ; communicated by Sir JofepU 
Banks, Bart. P. R. S. 



Kead January 27, 179U 

ALL our opinions on the fornmtion of rocks and mountains, 
except volcanic mountains, muft of neceffity reft upon 
analogical reafoning,fince we have uo dire<2 teftimony concerning 
their origin. Henfce, whatever portion of the mineral kingdom 
is but little conne<Sted with our experience of the aftion of fire or 
water, muft be flightly paffed over, or fet afide for future invefti- 
gation, while the partizans of the two oppofite hypothefes, 
which at prefeht divide the philofophical obfervers of foffils, fix 
their whole attention, and lay all the ftrefs of their arguments, 
on fuch particulars as they are able to conne6t by fome ana- 
logy with the chemical operations in which cither fire or wa- 
ter are principally concerned. For this reafbn, bafaltes has been 
much more the fubje(ft of difputation than granite ; the former 
fpecies of rock offering appearances that coincide in fbmc degree 
with both kinds of chemical proccfles, while the latter feems 
to ftand aloof from the experiments that have given birth to 
our fciences. We do, indeed, find opinions on the produftion 
of granite by one or other of the caufes above mentioned ; but 
they are generally * loofe conjeftures, thrown out at random, 
rather than philofophical propofitions, laid down in precife 

♦ The only exceptions known to me are, Phil, Tranf. Vol. LXV. p. 5 — 47. 
and Edinburgh Tranfaaions, Vol. I. p. 255—257. 

5 terms, 



Dr. Bedooes's ObfervationSj &c, 49 

terms, and fupported by proper evidence. In confequence of 
information obtained from various fources, I have been led to 
confider this queftion in a light fomewhat new ; and although 
I cannot but expeA my conclufions to be controverted, how- 
ever ftrong may be my own convidion of their juftnefs, 1 am 
encouraged by the hope of communicating fome original ob* 
fervations on the phyfical geography of our own country, and 
of bringing forward to public notice fome fa£ts not generally 
known among us, though they are fuch as cannot be over- 
looked in a theory of granite. 

Notwithftanding the recent objeftions of Mr. Werner *, 
I (hall aflume the origin of bafaltes from fubterraneous fufion as 
thoroughly eftablifhed by various authors +. Several obfervations 
of my own, which I intend foon to offer to the publick, will, 
1 flatter myfelf, corroborate the evidence, though already fuf- 
ficiently flrong to remove all reafonable doubt, and add a con- 
fiderablc traft to thofe where the effeSs of ancient fire have 

* Bergfixiannifches Journal, March 1789* Among the fadb addueed by 
this celebrated mio^ralogift to prove the wateiy origio of bafaltes, I cannot 
difcover any very new or ilriking. The appearance of bafaltes between ftrata is hit 
great argument. But the fame, or a ilmilar appearance had been noticed by Dr. - 
HuTTON (Edinb.Tr. T. p. 279.) ; Whitehurst (Chap. XVI.) : Ferber (Italy, 
p* 51.) mentions the infertion of lava between calcareous ft rata ; and in Leskb 
(ReifedurchSachfen, 4tOy 1785, p<5i70t we have bafaltic columns in fandfione. 
Mr. Werner alfo infifts upon the gradual approximation of the adjacent ftratum 
towards the nature of bafaltes. 

t Desmarest, in his welUknown Paper in the French Memoirs; Raspe, 
Extind Volcanos near Caifel ; Faujas, Volcans eteints, &c. and Mineralogie des 
Volcans; Sir W. Hamilton, Campi Phlegraci, and Phil. Traftf. ; Ferrer, 
Travels through Italy ; Dolomiev, in his Account of the Lipari and Pontian 
Iflcs •, Leske, /• c. ; Beroldingen, in his Account of the Quickiilver Mines 
in the Palatinate, &c.; Hamilton, Letters on the Coaft of Antrim; Hutton, 
/• c.\ Veltheim, Ecwas iibcr die Balalt, Leipfig, 17^7 S ^^ among the chief 
of thefe authors. 

Vol. LXXXr. H been 



50 Dr. Beddo£s*8 Obfervations on the 

been traced in our times* It may be proper to premife, that 
under the term bafaltes I comprehend that vafl nutaral Amtly 
of roclcs which is frequently cracked into regular colonnades, 
and may be followed in an unbroken feries from this perfeA 
form through endlefs modifications to the moft fbapdefs mafs 
of trapp or whinftone. Though freqxiently of an iron-grey 
colour and uniform texture, this fpecies of ftone varies greatly 
in both theie characters, even in the fame rock. In particular, 
it pafles, by the moft infenfible gradations, both to the por* 
phyries, with which it coincides in appearance, in coinpofi* 
tion, and doubtlefs alfo in origin, and to the bomjliln of the 
Germans ; a term including petrofilex and feveral forts of cldfe 
grained whinftone, of which I have found in England varieties 
with a conchoidal fracture, femi-tranfparent at the edges, and in 
other refpeds faft approaching * to a filiceous nature* Litle(hall 
Hill near Shifnal, in Shroplhire, to mention a (ingle inftance, 
affords fuch filiceous, befides Jemi-gfanttic^ porphyritic, and 
common whinftone, containing agate. 

But bafaltes, of which a right knowledge is conducing us 
faft to a juft theory of the earth, is not lefs connected with 
granite ; infomuch that we may trace tbefe rocks gradually ap* 
froacbing and changing into one another. I have myfelf had an 
opportunity of examining many connecting links in this gra- 
dual fucceflion ; and this opinion, which has fince been con- 
firmed by other confiderations, was firft forced upon me by 
fpecimens in great variety from volcanic and bafaltic countries. 
But as it is a point by far too important to be admitted on the 
mere authority of any mineralogift, I (hall endeavour to fup- 
port it by the teftimony df obfervers, who cannot be fufpedted 

* DoLOMXEU, Ifles Ponces, p. iii, 185. be. defcribes juft fuch layas» 

a of 



J^nity between Bafaltes and Granite. 51 

of any bias towards fuch an hypothefis. The firft ftcp in 
tht progreflion appears at the Giant*^ Caufeway in Ireland. 
Many of the pillars there confift of fine-grained, dark-coloured 
whinftone; that. variety which may be confidered as mod 
perfeft, and as cquidiftant from porphyry, petrofilex, and 
granite ; but at the promontory of Fairhead, the character of 
the ftone is ieen to alter, and it has lately been defcribed as an 
imperfect kind of granite^. Hence we are led by ^regular 
approaches to perfedi prifms of granite, accompanied by prifms 
of common whindone, and not lefs obvioufly than the dif« 
ferent ranges on the Coaft of Antrim betraying a common 
origin. The pillars of Les Rameaux, though they rather 
incline to^yards the dark colour and uniform hard fubdance ; 
^^ yet, when broken, are unequal both in colour and texture, 
** and fometimes interfperfed with irregular pieces and patches, 
^^ as it were, of an heterogeneous hard fubftance, which, by 
^^ its micae and fmall rhpmboidal cryftallizations, much re- 
** fembles a fort of granite 1 have frequently feen. The 
" mafs on which thefe columns ftand is of the fame mixed 
" charafter +.'* Other examples will occur afterwards ; and 
for bafaltiform colonnades of granite it is only necefTary to 
refer to Mr. Strange's defcription of Monte Roflb t. The 
general ftiape of the Euganean hills, as if fuddenly raifed by 

• Hamilton, 2d edition of his Letters, p. 37. fays, it" rcfcnnbles an imper- 
it^ compad granite/' I have fpecimens from an hill near Mallwhyd, in the vicinity 
of Cader Idris, where the texture infenfibly changes from an uniform whindone 
ground to grains of mica, feidfpath, ihoerl, and, I think, fometimes quartz. 
They are, I fancy, like thofe denfe lavas of Etna, " Qui,' vues ^ la loupe, laiflent 
appercevoir des ebauches de cryftallization de ihorl, de quarz, ou dc feld-fpath. 
DoLoiixEU, L c. p. 182. 

t Stxangk^ Phil, Tranf. LXV. p. 13. 

X Ibid. 

H z the 



52 Dr. Beddoes^s Obfervations on the 

the expanfive and efFervefcent force of heat * from the fur- 
rounding plain, the lava intermixed with granite, as if both 
had concreted together, the columns of an uniform texture in 
the adjacent parts of thefc hills, and the reft of the phaenomena, 
even then led the author to fufpeft, ** a ftrong analogy be- 
" tween granites and many particular volcanic concretions/* 

From the mountain of Efterelles, in the South of France, 
on the road from Frejus to Antibes, I have before me granite, 
gneifs, and fpecimens, in which feldfpath and grains of tranf- 
parent quartz are difFufed through a pafte of the fame brownifh 
red colour and texture as the bafaltic columns at Dunbar in 
Scotland. 

Nothing is indeed more common, or more varioufly modified, 
than foflils of this intermediate charafter +. We frequently find 
a ground of jafper, and no doubt alfo of different varieties of 
whinftone, as will hereafter appear, with feldfpath and (hoerl 
at the fame time imbedded in them | ; and again with grains of 
feldfpath and quartz in fuch a manner as to leave it extremely^ 
doubtful, whether the rock ought to be named granite or por- 
phyry §. The varieties of fuch rocks will conduft us, by eafy 
fteps, from uniform bafaltes through the porphyries to granite. 
A chemical examination of the bafis of a number of thefe por- 
phyries would be very interefting ; yet I would not reft the 
theory of their formation altogether on the refult of analyfis, 

* The fight of them impreflcd Ferber alfo with the fame idea, 

f II n*y a point dc naturaliftes qui nc connoiflent le genre de roches, place cntre 
le granit, Ics gneifs, ct Ics porphyrcs,qiu'tiennent iin pcu des trois efpeces. Iflcs 
Ponces, p. 90, 

X Haidinger, Trad quoted below, p. 47. 

§ Charpentier (Mineralogical Geography of Saxony, 410, 1778. in Ger- 
man), p. 50, and elfewhere, finds bimfclf in this ftatc of uncertainty. 

The 



^nity between Bafaltes and Granite. 53 

The fame ftratum is perpetually varying in its mixture; and 
we (hobld not too rigouroufly adhere to the proportion of in- 
gredients difcovered by the chemift in the hundred grains upon 
which his experiments may chance to be made. The fenfible 
qualities, the ftile of fifiure, the accompanying fofHls, and the 
form of whole rocks, when furveyed by an experienced eye, 
are as good crtterions of bafaltes as a certain proportion of iron, 
and the black glafs which it yields on fufion. Should the 
matter of any given rock contain too little -iron to be fufible by 
the blow-pipe, and yet have other flriking features of whin- 
fione, would this be a fuffioient reafon to conclude, that its 
formation has been different ? Chemiftry, if thus Hx'i&Xy fol- 
lowed, would perplex mineralogy, inftead of reducing it to 
order. Chara£ler$ of minerals, purely chemical, would fepa- 
rate tbofc whofe natural hiftory is alike, and bring together 
fuch as differ widely in their formation. 

The late Mr. Ferber's letters from Italy furnifli fo many 
fads, confpiring in one way or another to (hew the affinity 
between bafaltes as well as other produds of fubterraneous^ 
fire and granite, that whoever reads thena with/ this view will, 
I am perfuaded, find himfelf more interefled and inftrudted. 
The following are among the mod ftriking of thefe fads. 

" 4th fpecies of bafaltes. Oriental bafaltes through which 
" the conftituent parts of granite are equably diffufed. Sepa- 
*• rate particles of red feldfpath, quartz, and mica, are 
** difperfed through the fubftance of this fpecies : they feem to 
'^ have been didributed through an aqueous folution, and to 
*^ prove, that this fpecies had rather an aqueous than a fiery 
** origin." I fee neither proof nor prefumption in favour of 
this fuppofition ; but in a feries of fpecimens, collected with a 

view 



r^/^ :Dn BsDOOBs^i Ohfcrvathtu.otk the^ 

view to (hew the traufition frooi block bafaltesto.grauite, this 
ipecbs and the grauke from Ed^rdlea would form twacoa- 
tiguGua Hnks. 

^' 5th Oriental baialtes, with fbipes o£ gratiite. The 
^f oommoa bkck baialtes, fafciated with large firipea of red 
V granite, blended and joined to the bafakes without any 
^y viiible reparation ; not as the pebbles in a breccia, or as^ 
^^ fifTures healed'up and filled with granite, but as if botk the 
«^ bafaltes and granite had been fluid together ^/* 

Thofe fpccicnens, which (hew how copbufly volcanos produce 
feldfpath, (boerl, and mica, efpecially the two former (fubftances 
common both to bafaltes and granite), tend greatly to efta- 
b]i(h the near relalion between theie two kinds of rock. I 
was furprizedi at • this day, to find • an' excellent obier\rer 
ferioudy maintaining, that thefe earthy crydallizations are 
merely ejeded, and not generated, by thefe fires f • 

Attempts, I am aware, have been made to fet up boundaries 
between the columnar granite of the Euganpan hills, the 
granite of the volcanic provinces of FrancCji the granitello of 
the Italians, and fuch granite as is found to conftitute high 
and extenfive ranges of mountains* As to a difference in 
the fize of particlesi, and hardnefs of the ftone, the firft 
diftindion is neither conftant, nor by any means calculated to 
perfuade us, that a craufe, capable of producing the one, is 
inadequate to the produdion of the other. It may probably 
be explained from the quantity of matter, more or lefs perfe£t 
fufion, a different length of time in cooling ; and in the latter 
character I fufpei^ the obfervers to have been deceived by the 

* See Ff RW£R*s Travels in Italy, pp. 231, 232. Englifh tranflatiou. 
t DoLOMiEU, Ides Ponces, and Laves de TEtna, paffim. 

decay 



j^iiy -Mveen BafaUes and Granite. 55 

decay 6f the rocks they infpe^^ied *. At all evcntis, lavas ia 
abondarrce ihew, that fire is captabfe of producing any required 
ddgree of xompadtnefs +. 

IrfhiatH conclude this induction of particulars with an bbier* 
vatibn lately 'publifhed by one of ourmoft intelligent minera- 
lexical travellers. ** Aoidng the ancient black ftones, the 
** coDoipouiTd fpectes are moft frequent.- They often confift of 
•* tf land qfgranite^ in which th« fcaly black fhoerl predominates 
'^ fo much, that the wbolemafs appears black. It is accompa- 
" nicd ty white &ldfpath of fo froall a grain, and fo entangled 
^^ ailiong the (hoerl, as to be fometimes fcarcely diflinguifliable. 
^* The feldfpath itfelf is fometimcs tratifpafenrt, and by tratif^- 
*« mittmg the colcrur of the ihoerl, hi which it is imbedded 
^ (empdte) appears black . • . . • Sometimes fcales of black 
" mica bccur. The conftitueht parts do not always obferve 
••the feme proportion ; and when the quantity of feldfpath 
*• increafes, the 'appearance of a «*cal grey or red granite is pro- 
*< ddCed, Hence ^c have veins ahd fpots of grey granite in 
<«almoft 411 the daiic-coloured rodcs that pafs under the 
•* denomiifation of bafaltes. Thefe veins have very much 
•< embarralTed thofe naturalifts who maintain that all bafaltes 
" has* been produced by fire/' This circumftance, however, 
according to my view of the fubjed, is far from embarraffing : 
I confider it as a ftrong proof of my opinion, finCe it feems to 
involve this confequence, that, if bafaltes proceed from fufion, 
granite alfo itouft. Specimens, fuch as thofe here defdribed, I 
^ould place near granular bafaltes, like that of Cape Fair* 
head. "In blocks of ancient bafaltes,'* proceeds M. Dolo- 

^ << Thongh partial fpot$ of this granite are often friable, efpecially about the 
furface, jret in general it is veiyhard/' SraANGB, ubi fupra, p. 9, 
t See DoxoHXEV, liles Ponces, p. 139. 

MISU9 



56 Dr. BfiDDOEs's Obfervations on the 

MiEU, "I have obferved the tranfition from (hoerl in a 
" mafs nearly homogeneous (I fay, nearly homogeneous^ be- 
** caufe I know of no ftones, belonging, as thefe do, to the 
«^ primitive ihountams, without indications of a feparation of 
' *' feveral fubftances which were incorporated together in a 
«* pafte, or rather which are generated in that pafte) to black 
V and white granites, with large grains, and compofed of 
** nearly equal quantities of white feldfpath and black flioerL 
" The tranfition depends altogether on an increafed proportion 
** of feldfpath and on the enlargement of its grains ; a 
*' phenomenon which leaves no room to doubt, that all thefe 
." ftones belong to the fame fyftem of mountains V* 

By obfervations like thefe, which the fpecimens I either 
poflefs, or have examined, corroborate and compleat, I am 
perfuaded, that when once, it becomes an object of attention^ 
perfonswho have an opportunity of exploring countries where 
bafaltes and granite abound, will eafily find a fucceflion of 
fpecimens beginning at the former and terminating at the 
latter. Nor is it perhaps difficult to aflign highly probable 
reafons, why a mixture of different earths with more or lefs 
of metallic matter, in returning from a ftate of fufion to a 
folid confiftencc, may affume fometimes the homc^eneous 
bafaltic^ and fometimes the heterogeneous granitic internal 
flru£ture. No fad is more familiar than that it depends alto- 
gether on the management of the fire, and the time of cool- 
ing, whether a mafs (hall have the uniform vitreous fra^ure, 
or an earthy broken grain, arifihg from a confufed cryflalliza- 
tion. The art of making Reaumur's porcelain confifts en- 

* Journal de FhyGque, September 1790, p. 196. I have fereral fpecimens 
from the whin rocks about Edinburgh perfectly anfwering to this defcription, 
and fo like fome Vefuvian lavas that it is impoffible to diftingufih them. 

I tirely 



^JUntty between Bqfaltes and Granite. 57 , 

tirely in allowing the black glafs time to cryftallize by a flow 
refrigeration ; and the very fame mafs, according as the heat is 
conducted, may» without any alteration of its chemical con«* 
flitution^ be fucceflively exhibited any number of times as 
glafs, or as a ftony matter with a broken grain. In the flag 
of the iron furnaces, the fame piece generally exhibits both 
thefe appearances ; the upper furface cools faft, and is glafs ; 
what lies deeper, lofes its heat mqre gradually, and is allowed 
time to take on the cryftalline arrangement peculiar to its 
nature, in as far as a number of cryflals, flarting from various 
points at once, and crowding each other, will admit of it. 
Here indeed the cryftals are uniform, and not of a different 
form and compofition, as in granite; fb that this analogy 
applies clofely only to bafaltes ; and it pei-fedly explains why 
this body in congealing has aifumed an earthy and not a 
vitreous grain. But it is eafy to conceive how, under certaia 
Yariations of heat and mixture, a melted mafs may coagulate 
into quartz, feldfpath and flioerl, or mica*. The moft 
permanent difference between bafaltes and granite, as to mix* 
ture, confifts in the quantity of iron ; for the earths in the 
innumerable varieties of each vary indefinitely in their propor« 
tions ; and as to beat,, that the latter having been perhaps in 
general raifed from a greater depth, and cooflfling of more 

* ** II eft certain que dans les porphyres les criftaux de feld-fpath n'exiftoient 
pais avant Tepoque de la precipitation de leur bafe.*^; He fuppofes them to be of 
aqueous origin ; but the fa^ it much to my prefcnt purpoie. ** On j fuit let 
progres fuceeflifi de leur formation : on voit qu^ peu k peu let fubfiancet qui leur 
foDt propres fe rapprochent, sVpurent et prennent les formes qui conviennefit k 
leurs molecules ; ils etoicnt comme en diflblution dans leufs matrices et ils ont 
d'autant plus de facilite a fe joindre que la fluidite a ith plus parfaite et que le 
dcflcchement a et6 plus long.*' Ifles Fonces, 247, 248. 

Vol. LXXXL I huge 



58 Dr. Beddoes*s Obfervattons on the 

huge mafles, muft have cooled more flowly, and perhaps they 
have undergone different degrees of fufion. Beikles toadftone, 
bafaltes incloHng feldfpath, zeolite, &c.9 various lavas clearly 
demonftrate that heterogeneous earthy cryftals do feparate from 
a fufed paf^e, once undoubtedly as uniform as a metallic calx and 
its reducing flux before the fubfidence of the metallic particles. 
We (hall, I imagine, be much deceived by a narrow analogy 
if, becaufe in our procefles for glafs-making an homogeneous 
product is obtained from heterogeneous materials, we conclude, 
that an heterogeneous produ£t may not, under other circum- 
ftance$, refult from fufion; and that fire keeps infeparably 
blended whatever it has once reduced to an uniform liquid pafte. 

It muft alfo be carefully remembered, that this difficulty 
does not prefs the igneous more than the oppofite hypothefis. 
Since the conftituent parts of granite are cryftals, the whole 
mafs muft once have ^xifted in that ftate of entire difunion of 
its particles which is neceflary to cryftallization* Now, whe- 
ther fuch a folution have been efFeScd by the repulfive power 
of fire, or the intervention of water, it is juft as eafy to con- 
ceive heterogeneous earthy cryftals (hooting from different 
points of an uniform liquid, according to the former fuppofition^ 
as the latter. 

In the natural hiftory of granite and bafaltes, another 
ftriking circumftance occurs : they Info contiguous^ and are Jo in^ 
vohed in me another^ that we cannot but fuppofe both to have 
undergone the fame operations of nature at the fame time. This 
18 feen with the utmoft frequency upon every poifible fcale^ 
and under a vaft variety of modifications. The fadts already 
quoted afford inftances in point. I have before me a fpecimen 
from the park at Stockholm, confifting partly of trapp and partly^ 
of granite* The adjacent parts are as firmly united as the other 
7 parts 



JStnity betwten Bafajtes and Granite. 59 

parts of the fpecimen ; and when a violent blow is Aruck, 
the trapp and granite do not feparate, but the fra£lure takes 
fome other direSion. They ieem it) feveral places of the 
boundary to run into one another. The whole mountainous 
diftrid furveyed by Mr. Leske * with fuch fcrupulous accu- 
racy affords multipiied examples of the contiguity and connec- 
tion between thefe different rocks. " From all thefe minute 
" defcriptions,^ fays the Author, " it appears, that the bale 
" of the whole range coniifts of granite. On the declivity of 
" the higheft elevations, and on the folitary fummits of the 
" external chain, corneous porphyry lies upon the granite, out 
^< of which as well as the granite itfelf, and the fandftone at 
^ its foot, bafaltes has been protruded by the force of fubter^ 
** raneous fire +/' The manner of connexion will appear 
from a few examples. The bafaltes of the Spizberg | has a 
granulated firu&ure, and is imbedded in granite. The fub- 
ilance of the pillars of the Gikelfberg § is clofe and granular : 
in fome pieces ^* I found the conftituent grains of granite little 
** altend.^^ Of the columns of the Knorberg, ** the fubftance 
^* is clofe, uneven, and coAfifls of difiinA grains i . . S large 
*^ pieces of itnperfeSly fufed granite are diffufed through its 
^* fubftance. In the Whinftone of the Hochwald there are 
^^ found pieces confifting of a mixture of white feldipath, 
^^ quartz, and black ihoerl ||/* Again, in the Rauberg, the 
conftituefit parts of granite are fo diffufed through the ba&ltes, 

• Rcife chirch Sachfcn. 

t Ibid, p* 513* ** It is alio remarkable, that granite in general throughout 
Velay and Auvergne is frequently intermixed with the bafaitiseand other common 
volcanic hills. I have obferved the fame in Italy.?' STJaAVOi, p. 14. 

X Reife dureh SachfcD, p. 398. 

§ Ibid. p. 498. il Ibid. p. 515. 

I 2 that 



6o Dr. Bedsoes's Obfervations on the 

that the Author imagines the rock to be an imperfectly i\x{e^ 
granite *. I rather confider thefe as inftances of imperfeftly 
cryftallized granite, where fome unfavourable circumftance 
has prevented the conftituent parts from receding completely 
from one another. * Experiments (hew, that almoft all granites 
melt into a black glafs -f ; and perhaps it is no abufe of analogy » 
nor inconfiftent with what I have already remarked, to con«- 
elude, that granite, in the (late of imperfed fufion, fhould pre-^ 
fent a glafly fubftance, involving the more infufible parts of 
which this (lone con(ifts. 

The Scheibenberg, near K6nig(bruck, confifts of a (lone 
which Mr. Leske knows not whether to call hornflatej, or 
corneous porphyry §. From the defcription it appears plainly 
to be a whin(tone. The colour is dark grey ; it breaks inta 
columnar fragments ; is hard, fine-grained, znd Jbnorous ; little 
veins of quartz crofs it in all diredlions, and it frequently 
becomes porphyritic, as enclo(ing cryftals of feldfpath. The 
Author himfelf is afterwards aware || of its affinity to bafaltes^ 
both in fubftance and from its afTuming the columnar form* 
In this hill a mafs of granite is found imbedded in the whin* 
flone, and on all (ides furrounded by it, and the mafs of 
granite is in its turn in all diredions interfed:ed with veins and 
itripes of - whinftone. Mr. Leske is much (Iruck by this 
mutual and intimate incorporation ; but he makes no attempt 
to explain it. In fome inftances, he thinks an eruption has 

* Rcifc (lurch Sachfen, p, 330. 

t Haidinger's Einthcilung dcr Gebirgiarten. Wicn, 1787, p. 11. and the 
Authors quoted there. ' 
J Hornfchiefer. 

§ Ibid. p. 24 — 29. No chemical charaftcrs are giYcn. 
I Ibid. p. 513, 514 

I broke 



jiffinity between B a/a lies and Granite. 6i 

broke out through the granite ; and in others, is at pains tp 
(hew, that thefe fubftances are not thoroughly blended, as iu 
the laft example, and in that delcribed by Fbrber. 

It may be faid, and no doubt it fometimes happens, that 
Olivers of granite, broken off by the violence of explofion, 
are licked up by melted matter as it moves along ; thus, ia 
volcanic breccias an older lava is inclofed in one more recent, 
and thus what is called primary is fometimes encafed in fecon- 
dary granite. But fuch an hypothefis is too narrow to embrace 
all the phenomena. It does not explain the incipient coagula- 
tion .of the uniform pade into grains, and thofe the different 
grains of granite ; nor the diffufion of the conftituent parts of 
granite through the fubftance of bafaltes ; nor the fifth fpecies 
defcribed by Mr. Fbrber. 

In V the whinftone rocks of England, which are far more 
numerous than is commonly fuppofed, I have frequently ob- 
ferved in the fame hill, i . homogeneous dark grey ftone ; 2. 
feldfpath enclofed in this as in a pafle ; and, 3. the pafte difap- 
pearing, and the whole becoming granular, and the grain's 
heterogeneous. Beiides feldfpath, quartz is found in innu- 
xncrable mafles of varying magnitude * in many whinftone 
rocks, and as proper bafaltes is but a confufed mafs of cryftals 
of ihoerl, we have all the ingredients of granite ; and why 

* In the Wrekin, Cader Idris, &c. numerous and large veins filled with 
quartz occur ; but thefe have not been Jtcreied from the fubftance of the rocks 
io which they He. They, perhaps, (hew this moft filiceous ingredient of granite 
to have been near and in fufion at the fame tipe. About Cader Idris I fufpiedt an 
incorporation of granite and bafaltes may be found. I have feen pieces of granite 
about that mountain which did not feem to have been fir removed from the rock 
to which they belonged ; but I had then no particular inducement to make an 
accurate examination. 

may 



ti Dr. Beddoes's Obfernyations tm the 

may we not expedl to find them incorporated together, and in 

every ftate of diffufion and reparation ? 

Under this head I (hall only remark farther, that feveral 
late obfervations, from which it has been inferred, that certain 
extinft volcanos liave been feated in the heart of granite*, feem 
to admit of a much more eafy explanation, on the fuppofition 
that granite has cryftallized from fufion. i. Volcanic fire^ 
reach to a much greater depth than any at which we have had 
an opportunity of making obfervations. The focus in different 
inftances may be feated at a different diftance from the furface ; 
but none are probably lefs than feveral miles at leaft deep. 2. 
The currents of granitic lara + in the Pontian ifles leave little 
room to doubt of the power of fubterraneous fire to produce 
this fubflance. To fuppofe them to be rocks of granite fufed, 
but otherwife unchanged, and that even fiflile rocks may be 
made to flow without lofing their laminated flrudlure; is as bold 
an afTumption as can eafiJy be taken up. In the great igneous 
procefTesof nature fire need not be imagined to aft otherwife J 

* DoLOMiEU, Ifles Ponces, p. 30, 31. and Ifles de Lipari, in various parts. 

f DoLOMiEU, /. f. paffim^ and particularly p. 89 — 97. Inftru6tivt as the 
particular fa£b defcribed by this excellent mineralogid always are, I muft diiTenC 
from him both on the mode of a£tipn of volcanic fires, and on the produdtion of 
zeolite and other cryfials, in glandular rocks, for the reafons afEgned here and 
belonr. 

% <' Le feu produit, dans les laves, une fluidite qui n'a aucun rapport avec la 
fluidite vitreufe que nous operons . . • . • Celui des volcans n'a point d'inten- 
fite ; il ne peut pas meoie vitrifier les fubftances les plus fufibles • • • .^il pro« 
duit la fiuidtte par une cfpece de diflblution, par une fimple dilatation qui permet 
aux-partijts de glifler les unes fur les autres (Dolomieu, Avant-propos, p. 8.). 
See alfo p. 84. Fire in a crucible produces fluidity no otherwife ; and whta 
there is this freedom of motion among the fartieUs^ how can we fuppofe the 
ctyftals of granite and the leaves of fchiilus to remain unmixed even in a current 
of lava ? 

than 



jiffinity between Bafaltes and Granite. 6j 

than in our fmall experiments; we adually fee it producing 
glafs and cellular fpongy fcorise : when the produfbs are of a 
different charafter, we mufl have recourfe to acceflbry circum- 
(lances, and not violate the plaineft rules of philofophifing by 
attributing different effects to the fame caufe. The latent mo- 
tive for fuch an extraordinary hypotheiis may eafily be divined ; 
the obferver took it for granted, that all granite is of aqueous 
formation ; hence he was obliged to reafon backwards from 
the unknown^ that of the Alps for inftance, to the known^ 
inftead of proceeding from the palpable effedts of fubterraneous 
fire by cafy fteps to a general, 'theory of granite. When it is 
taken for granted, .before examination, that granite cannot be 
formed by fire, there remains no refource but to fay, that gra- 
nitic ♦ lavas are granite rocks fufed, but not altered in the 
arrangement of their conftituent parts. 3. Though the heat 
of volcanos be fometimes and in fome places moderate ; in 
others we have good reafon to believe, that it exceeds any de- 
gree we can produce, except by means of faditiou^ air ; we 
are certain that it forms molten currents of petrofilex and flint 
exaftly the fame as our gun flints +. 

If we admit this reafoning, the appearance of granite in the 
bofom of volcanic defolation may^ if duly examined in all its 
circumftauces, afibrd ftrong evidence of its production by fufion ; 
and it is reafonable to conclude, that it was once covered to a 
oonfiderable depth by erupted matters, which the courfe of 

* ^' Les laves blanches de Tile Ponce paroiflent appartenir plus particuli^re* 
ment au granit et aux roches feuilletees granitiques. On reconnoit les fubfiances 
qui confiituent ordinaireroent ce genre de roche compofee dans prefques toutes les 
niati^rcs blanches (volcaoiques) de cette ifle ; &voir, le quartz en grain, le mica 
ooir ecailleux et k feldfpath plus ou moins pur. Dolomx£U, /. c» p* 89* 

t Idem ibid. p. 107. 

tinae^ 



6+ Dr. Beddoes's Obfervations on the 

time, and the injuries of the atmofphere, have removed ; 
though I by no means deny that a volcano may force its way 
through pre-exifting rocks of granitei 

There is flill another analogy between bafaltfes and granite, 
more important to the theory of the earth, and lefs liable to 
controverfy than either of the preceding. In their Jituation^ 
with refpe£i to other rocks^ we may obferve^ the fame law. The 
general rule of fupcr-pofition, reckoning from below upwards* 
is, I. granite; 2. fchiflus; 3. limeftone. This rule has 
been found to hold good by fo many mineralogical travellers 
that, though it may not be abfolutely univerfal, it muft be 
allowed to prevail very extenfively. Now, in this ifland there 
are numerous inftances where bafaltes is fubflituted in the feries 
indead of granite, and where it feems to alternate with gra- 
nite as the fubflratum of other rocks. On the road from: 
Doigelly in Merionethfliire, by Mall why d and Cann's Office, 
through Llanfair to Wclchpbol, fchiftus appears always in- 
cumbent on whinftone, except fometimes when the latter is 
interjedied between the ftrata, or fqueezed up through fiflures* 
In Wales the country is fo hilly, that the limedone, if it 
exifted, has probably been wafhed away ; but on the confines 
of England it comes in. The road from Wekhpool to 
Shrewfbury paflTes over the fide of the Long Mountain, which 
confifts of fchiftus ; on the left, or towards the eaft, rife fome 
confiderable bafaltic hills. The ftrata of the Long Mountain 
point towards the fummit of thefe hills, as if the narrow 
valley that intervenes had been cut by water upon the lifted 
edge of the fchiftus. At a fmall diftance from the north an4. 
ibuth fides of the bafaltic hills calcareous ftrata are found. 
Beyond Shrewft)ury, on the road to London, we have, inftead 
of the continued ridges of Wales, a number of iufulated, and 

generally 



j^nity between Bqfaltes and Granite. 6^ 

generally rugged, points, rifing over the face of Shropfhire 
and the adjacent counties. Were the plains covered with 
water a few yards in depth, thefe eminences would appear 
from didaoce to diftance like fo many ftepping ftones. They 
all, except the Malvern Hills, which, though compofed of 
granite, I confider as part of the fame fyftem, conlift of whin- 
fione. Among thefe ilepping ftones I reckon the bafaltic hills 
near Welflipool, the Wrekin, Lillcfhall Hill, and, at a greater 
diftance towards the Eaft, the rifing grounds near Newcaftle ia 
Stafibrdlhire, whence the whin rock, perhaps, communicates 
by the toadflone of Derbyfliire, through the hills in the North 
of England with the whinftone tbwards the South of Scot- 
land. In a fouth or fouth-weft diredion from the Wrekin, a 
number of craggy eminences arife. They are bafaltes, and 
form a ftriking contrail with the fmooth, rounded, and 
lumpifli fwells of fchiftus in their neighbourhood. From the 
whin rocks near Stretton we may pafs by the Brown and 
Titterilone Clee Hills (on the latter of which are regular prif- 
matic columns) to the Malvern Hills. About thefe hills lie ft rata 
of fchiftus and limeftone, as is feen on the road from Much 
Wenlock to Stretton. To the Ibuth-eaft an extenfive field of 
whinftone, with occafional elevations, is fpread over the confines 
of Worcefterfliire, Warwickfliire, and StafFordfliire. Here we 
have the Rowley ragftone. Whether the bafaltes proceeds 
fouthward by fuch interruptions till it join the Elvin or 
whinftone, and granite of Devonfliire and Cornwall, where 
I imagine they may be found incorporated, I wifli for an 
opportunity to examine. In the plain part of this whole 
diftria, the whin rock appears frequently at the furface, or 
a little below the ftrata, fo that the hills have probably a fub- 
terraneous communication with one another, and there needed 
Vol. LXXXL K but 



66 Df* Beddoes's Obfervaltons on the 

but a little more lifting force to form continued ranges of 
mo^intains. The road from Welfhpool to Birmingham, above 
threefcore miles, is repaired in a great meafure with whin- 
ftone. A colonnade of bafaltes has been lately expofed in 
digging the Shropfliire canal; and in the mining country 
around, levels have been driven in the black rock, as it is 
(bmetimes called. As I have feen whinftone and flate in vari- 
ous other parts of North and South Wales, the whole weftcm 
(ide of our ifland has probably been raifed by the bafaltes on 
which the fuperficial ftrata now reft, though from particular 
circumftances the fufed mafs has now and then cryftallized 
into granite; and as it has been conje£tured, that the bafaltes 
of Ireland once joined that of the Scotch iQes and the main 
land itfelf, fo perhaps the bafaltes of North Wales joined the 
Iriih coaft till the fea worked its way or broke in, and de^ 
ftroyed the continuation. 

As Hmeftone is fometimes faid to reft immediately on gra^ 
nite *, fo at the foot of the Wrekin, and at Litlefliall Hill, 
IK) flate is interpofed between the limeftone and bafaltes ; fb 
tliat the analogy extends even to the exceptions. 

But another feries has been obferved, which fcems to con- 
neft granite by a clofer tie with the operations of fubterraneous 
fire. In Italy lava ftaads to fla*e and limeftone in the fame 
relation as granite and whinftone in other countries +. Whole 
ridges of mountains in the Venetian territory confift of folid 
lava, fometimes almoft bare, fometimes retaining the fuper- 
incumbent ftrata, with feveral local variations; all of which 
are reducible to a gceater or lefs dfegree of lifting force. Thcfe 



♦ Bo&n's Lcu^n, p» ao;. 

t F^Ri^R, /. c. pp. 42. 5.1. J aij<l ^fp^kiU/ Stkajiok, I ap..24T-3a* 



chains 



Affinity beltjoeen Bafaltes end Granite. 6j 

chains have a totally difFcrent form from the common conical* 
fliape of volcanos or heaps of loofe ejeded matters. They 
feem to afford a clear inftance of the manner ki which long 
continuations of mountains have been elevated; for It is not 
eafy to admit the fuppofition of the obferver, who has fo accu- 
rately deicribed them, that the limeftone has been .converted 
into lava ; and that the ridges exifted, fuch as they appear at 
this day, before this change was produced by fubterraneous 
fire. Chemical and mechanical confiderations are unfavourable 
to this hypothefis ; and " fince moft of thefe branches, whether 
" imrioc^ volcanic, or mixed, preferve nearly the fame exter- 
•* nal charad^ers, direftions, and parallelifm ;** it appear^ highly 
probable,, that they have not pre-exifted as hills in another 
Hate, but owe their elevation to the expanfive force of fire ; 
and that the fame lava which appears in fo many places lies 
alfo under all the limeftone bills, of which indeed there are 
evident indications. 

Several modern travellers have defcribed the ftrata of granite 
mountains ; but neither in their defcriptions nor drawings have 
I been able to find fatisfadlory evidence 6( this arrangement ; 
nor have I obferved it in nature. A liquid mafs fwelled by 
heat muft crack in cooling. Granite feems to me to hav6 
cracked mod: frequently like the bafalte en tables ; and thefe 
flat mafles have been taken for flrata. A ftratum, coniifting of 
proper materials to form whinftone or granite, may have 
been ezpofed to the neceffary degree of heat, and poflibly have 
undergone this change without much relative local derange- 
ment. Should fuch a flratum be difcovered, it would afibrd 
no proof of the ftratification of the great mountains of granite 
or (hapelefs whinftone, which, in ooufequence of its nu- 

K 2 merous 



68 Dr. Beddoes's Obfervations on the 

merous fiffurcs in all direftions, fometimcs aflbmes enough of 

this appearance to impofe on an unwary eye. 

One confequence of thefe obfervations is too important to be 
omitted. They lead us to rejedl the common divifion o£ 
mountains into primary and fecondary. The chains of granite^ 
fchiftus, and limeftone, muft be all coeval ; for if the central 
chain of the Alps burft as a body expanded by heat from the 
bowels of the earth,, it reared the bordering chains at the fame 
effort. But it muft be recoUeded, that the mountains no 
longer wear their original form, vallies having been cut. 
between and through them, and various other effe<Sls of dila- 
pidation having taken place. It is by no means difficult to 
underftand why no exuviae of organized bodies are found in 
thefe imaginary primitive mountains. Rifing from a great 
depth, they threw afide the fuperficial accumulations of the 
ancient ocean. What wa,s deepcft is therefore now moft 
central ; and what lay on the furface now Ikirts the high inte- 
rior chains. Hence the ftrata reft indifferently ou granite^ 
bafaltes, or lava ; all which fubftances derive from their fitua- 
tion an equal claim to be regarded as primordial materials. It 
is a little furprizing, that this inveterate error, which has 
efFe£lually barred the way to all great difcoveries in geology 
till of late *, fhould have prevailed fp long : for, i. it is well 
known, that granite is fometimes found encloiing pieces of 
fchiftus + ; nor are long ftretches of flate uncommon in moun- 
tains of granite J. Now, how can a fecondary be fo enve- 
loped in a primitive rock ? and how eafy is this to be under- 
ftood, if we fuppofe granite as a fufed mafs raifing, renduig, 

« Till Dr. Hutton's Theoiy of the Earth, Edinb. Tranf. Vol. I. appeared, 
t Bokn's Letters, p. 207, 208.. 
X Haidinger, /• €• p. i8. 

3 and 



j^ity between Bafaltei and Granite. 69 

and fliivering the incumbent ftrata, while its heat hardened them 
into laminated ftone. 2. Sappofing granite mountains previoufly 
exifting in the ancient ocean, the inclination of the incumbent 
ftrata, and their difarrangement is fuch that they could never 
have been depofited as they appear at prefent ; they would have 
been much more horizontal in their di region. It feems im- 
poffible to attribute the diforderly deviation, which is fo general 
in the mountains of flate, &c. from that pofition which all 
fediments from water affume, to any thing but a force lifting 
from below, and fometimesburfiing through. 

It is moreover certain, that all thefe lifting mafles, from 
granite to acknowledged lava ♦, are found fqueezed up through 
fiffures formed in the ftrata by their own expanfion. This^ 
and not the infiltration of water, as M. de Saussure would 
perfuade us +, appears to be the true origin of fuch veins of 
granite. 

* Ferber, /. r. p. 51* 

t Voyages dans Ics Alpcs, 410, !• 552 — 5j6. The whole paffage weU 
deferves the notice of thofe who are interefted in thefe enquiries. Vertical ftrata, 
10 oae in (lance, lying againft the foot of a granite mountain , are divided by 
oblique fifTures, full of granite* This naturalift fuppofes them to have filled up 
gradually by the rain water dillblving particles of granite, carrying them down 
and depodting them in the form of granite again ; two operations which one may 
iafely deny to rain water the power of performing. Other infuperable objections 
to this theory ftart up at every ftep ia the defcription. If water can dilTolve any, 
it is furely but a very fmall part of all the ingredients of granite. Now, fup- 
pofe a fifllire full of fuch a folution ; the water is, I fuppofe, to evaporate, and 
the cryftallizatioo to take place ; the cryftals muft be fmall, on account of the 
fmall quantity of matter to form them, and a fueceeding folution can only yield 
another crop of fmall cryftals, it will not enlarge thole already formed ; but we 
are told, tliat the cryftals of granite in the crevices in queftion are remarkably 
large. This has always appeared to me a chemical demonftration of the falfehood 
of a very common fuppofition, that the cryftals often occurring in the cavities of 

the 



•0 JD^. Beddoes*s Ohfarvatms^ &c. 

the amy gdaloidcf rocks have beea formed by the infilti-atioa of water. Thecryf(al6 art 
fre<|ueatly of fo large a fize that you can hy no means fuppofe the quantity of water, 
tt any one time exiding in the cavity, could have held the folid matter, of which 
they confift, in folution. Now, I think, it is contrary to all our experience in che« 
miftry, to fuppofe cryftals built up by fuccefGve operations. If upon cryilals ot 
nitre I pour a folntion of the fame fait, the former crydals will not be enlai^d 
and amended, but a new fet will be formed ; fo fucceffive quantities of water^ 
pailing through thefe cavities, ought to form fucceffive fets of very fmall cryftals* 
Neither can I imagine, what caufes can produce within thefe cavities a depofition 
•f the matter once diflblved by the water. It is not cooled ; it does not evapo- 
rate; it lofes no fixed air ; it comes in conta6t with no new matter, whofe attrac* 
tion may overpower the attraction of the water. 

The divifions, ^* rather marked out than formed^ which crofs each other 
irregularly (p. 533.}t ^Qd indicate an incipient retraction," are much more con- 
ddent with a iimultaneous congelation than a gradual appoiition ; and the granite 
is the fame as that of the contiguous hill in the colour and appearance of its 
conHituent parts. This coincidence is a finking fad. 

In truchy the philbfbphers who attribute the formation of graaite to water ieem 
not to have advanced a flep in their proof beyond the equivocal circumHaAca of 
its being a cryfiallized mafs. 




C 2« 3 



IV. On Nebulous Stars^ properly fd called. 
By William Hcrfchel, LL.D. F, R. S. 



Read February 10, 1791* 

IN one of mj late examinations of a fpace in the heavens^ 
which I had not reviewed before, I difcovered ajiar of about 
tbe %tb magnitude^ furrounded with a faintly luminous atmojpbere^ 
of a conJiderabU extent. The phasnomenon was fb ftriking 
that I could not help refie£ting upon the circumftances that 
attended it, whidi appeared to me to be of a very iuftrufHve 
nature, and fuch as may lead to inferences which will throw a 
confidcrable li^iton ibme points rekting to the conftrudlioa 
of the heavens. 

Gbudy or nebulous ftars have been mentioned by feveral 
afironomers ; but this, name ought not to be applied to the 
elyje^s. which riiey have pointed out as fuch v for^ on examina-- 
tion, they proved to be either mere cluflers of ftars, plainly 
to be di^inguifhed with my large inflruments, or fuch nebu- 
lous appearances as might be reafonably fuppofed to be occa- 
sioned by a multitude of flars at a vaft diftance. The milky 
Way itfelf, a^ I have the wn in ibme former Papers, confifls 
iatirely of ftars, and by imperceptible degrees I have been led 
on from the moft evident congeries of ftars to other groups in 
which the lucid points were fmaller, but fiill very plainly to 
be feen ; and from them to fuch wherein they could but barely 
be fufpe^ledy till I arrived at laft to ipots in which no trace ot 
4 afiar 



72 Dr. Herschel's Obfervations 

a flar was to be difcerned. But then the gradations to thefe 

latter were by fuch well-conne^ed fteps as left no room for 

doubt but that all thefe phaenomena werfc equally occafioncd by 

ftars, varioufly difperfcd hi the immenfe expanfe of the univerfe. 

When I purfued thefe refearches, I was in the (ituation of a 

natural philofopher who follows the various fpecies of animals 

and infefts from the height of their perfedlion down to the 

loweft ebb of life ; when, arriving at the vegetable kingdom, 

he can fcarcely point out to us the precife boundary where the 

animal ceafes and the plant begins; and may even go fo far as 

to fufpedl'them not to be effentially different. But recolleding 

himfelf, he. compares, for inftance, one of the human fpecies 

to a tree, and all doubt upon the fubje^l vaniflies before him. 

In the fame manner we pafs through gentle fleps from a coarfe 

clufter of ftars, fuch as the Pleiades, the Praefepe, the milky way, 

the clufter in the Crab, the nebula in Hercules, that near the 

preceding hip of Bootes (tf), the 17th, 38th, 41ft of the 7th 

clali of my Catalogues (^), the loth, 20th, 35th of the 6th 

.clafs(c), the 33d, 48th, 213th of the ift (rf), the 12th, 

{a) RA. ijh. 27' 40". PD. 60** a'. The jdaeet of all thcobjeat men- 
tioned in this Paper are not brought to. the prefeat time^ but given ai they urere 
calculated from the beft obfervations I have nuide of themi the change in their 
fitu^tion arifing from the iapfe of a few years is too trifling.to be any hindrance 
to our finding them very cafily. *^ 

{b) VII. 
(O VI. 



(^) I. 





„. ^' ' " 


/ 


17. 


RA. 7 9 45. 


PD. H4 34. 


38. 


6 S3 16. 


8837- 


41. 


22 20 2P. 


3847. 


10. 


16 14 22. 


US 3». 


20. 


42 4. 


117 46. 


35- 


1944. 


29 41. 


23- 


II 57 26. 


78 25. 


48. 


17 10 46. 


107; 36. 


ai3. 


12 17 59. 


44 45- 



150th, 



on Nebulous Stars. 75 

I50th^ 756th of the 2d (42), and the iSth, 140th, 725th of 
the 3d- (^), without any hefitation, till we find ourfelves 
brought to an objeft fuch as the nebula in Orion, where we 
are ftill inclined to remain in the once adopted idea, of flars^^ 
exceedingly remote, and inconceivably crowded, as being the 
occafion of that remarkable appearance. It feems, therefore, 
to require a more diffimilar objedt to fet us right again. A 
glance like that of the naturalift, who cafls his eye from the 
perfe£t animal to the perfed vegetable, is wanting to remove 
the veil from the mind of the aftronomer. The objeft I have 
mentioned above, is the phsenomenon that was wanting for 
this purpofe. View, for inftance, the 19th clufter of my 6th 
clafs(c), and afterwards caft your eye on this cloudy ftar (^,' 
and the refult will be no lefs decifive than that of the naturalift 
we have alluded to* Our judgement, I may venture to fa/^ 
will be, that the nebulo/ity about the Jlar is not of a Jiarry 
nature. 

But,, that we may not be too precipitate in thefe new deci* 
(ions, let us enter more at large into the various grounds which 
induced us formerly to furmife, that every vifible obje£^, in 
the extended and diftant heavens, was of the ftarry kind, and 
collate them with thofe which now offer themfelves for the 
contrary opinion. 

(a) II. la. RA. \% 32 37. PD. 72 23. 
150. 14 19 53. 81 43. 

756. 14 51 42. 35 22. 

(i) III. 18. 12 41 7. 84 S^- 

140. I 5 8. 92 o, 

725- " 6 57. 43 14. 

(0 VI. 19. IS 5 a. no 14. 

(^ 3 56 48. 59 SO- 

V0L.LXXXI. L It 



74 Dr. HeiiSCHXL*i Oijinfatlons 

it has been obferred, on a former occaiion, that alt the 
fmaUer parts of other great iyflems, fuch as the planttSt their 
rings and fatellites, the comets, and fuch other bodies of the 
like nature as may belong to them, can never be penceiTed bjr 
us, on account of the faintnefs of light refle£led from Qnsdlp 
opaque objects ; in my prefent remarks, therefore, all thefe are 
to be iatirely itt afide. 

A well conne<5ted feries of obje£bs, fuch as Mre have men« 
tioned above, has led us to infer, that all nebmls confifi of 
ftars. This being admitted, we were authorised Co extead our 
analogical way of reafoning a little farther. Many x)f the 
nebula had no other appearance than that whitilh cknidmefst 
on the blue ground upon which they focxxnid to be prq^eded} 
and why the fame caufe ihould not be afligued to explain the 
mod extenfive nebuloCities, as well as dioiechat amonntodonlj 
to a few minutes of a degree in £ze, did not appear. Ic couUI 
not be inconfiftent to call up a telefcopic milky way, at an 
immetiie didance, to account far fuch phaBnomena; and if any 
part of the nebulofity icen^d detached from the left, or con- 
taincd a vifible ftar or two, the probability of feeing a &w 
iiear ftars, apparently fcattered oi^er the far diftaot r^iont of 
myriads of iidereal collections, rendered nebuioos by their 
diflance, would alfo clear up thefe (ingularitiea. 

In order to be more eafily underflood in my remarks on the 
comparative difpoiition of the heavenly bodies, I (hall meation 
fome of ^ the particulars which introduced the ideas of connexion 
and diJjunSiion : for thefe, being properly founded upon an exa- 
mination of objefts that may be reviewed at any time, will be 
of confiderable importance to the validity of what we may 
advance with regard to my lately difcorertd nebulous ftars* 

2 On 



en Nebubmi Stari. ^5 

On June the %jt\ 1786, I faw a bcautifiil clufter of very 
fmall ftars of various fizes, about 15' in diameter, and very 
rich of ftars {a). On viewing this objeft, it is impofiiblc to 
withhold our aifent to the idea which occurs, that thefe ftars 
»e ccmneflred fo far one with another as to be gathered loge* 
ther, within a certain fpace, of little extent, when compared 
to the vaA expanfe of the heavens. As this phenomenon has 
been repeatedly feen in a thoufand cafes, I may juftly lay 
great^ftrefs on the idea of fuch ftars being conneAedr 

In. the year 17791 the 9th of September, 1 difcovered a very 
fmall ftar near • Bootis {b). The queftion here ^ccurring^ 
whether it had any conne£kion with i or not, was determined 
in the negative ; for^ coniidering the number of ftars fcatiered 
lii a variety of places, it is vtty far from being uiKommon^ 
that a ftar at a great £ftance (hould happen to be nearly in a 
Ike drami from the fun through i, a&d thus conftltute the 
obferved double ftar^. 

The 7th of September^ 17824 when I firft faw the plane- 
tary nebula near 1^ Aquani (r), I pronounced k to be a lyftem 
Wb«f<( pdtta Were conneAed together Without entering ioto- 
anyikmd of calculation) it is evident, that a certain equal 
degree of light withiti a veiy fmall fpace, joined to the particu*^ 
lar (hape this obje£t prefento to ua, which is ne^lrly round, and 
even in its deviation confiftent with regularity^ being a little ellip- 
CicaU ought naturally to give us the idea of a conjun&ion in the 
thitigs^ that produce it. Add a coiiiiderable addition to this 
argument may be derived from a repetition of the fame phae- 
oomenon, in nine or ten more of a finular conftrudion. 

(a) RA- i8h. aC of'. PD. 107^ 3'. 

{b) Phil.Tranf. Vol. LXXII. p. 115. Catjaogue of Double Scan, L i. 

It) RA* aoh. 5a' 36", PD. loa^ ia\ 

L % When 



y6 Dr. Uerscrsl^s Obftroations 

When I examined the clufter of ftars, following the heaSd of the 
great dog {a\ I found on the 19th of March, 1786, that there 
was within this clufter a round, refolvkble nebula, of about two 
minutes in diameter, and nearly of an equal degree of light 
throughout {b). Here, confidering that the clufter was free 
from nebuiofity in other parts, and that many fuch clufters, as 
well as many fuch nebulae, exift in divers part$ of the hea^* 
vens, it appeared to me very probable, that the nebula was 
unconnefted with the clufter ; and that a fimilar reafon would 
as eaiily account for this appearance as it had refolved the phae- 
nomenon of the double ftar near t Bootis ; that is, a cafual 
Situation of our fun and the two other obje<9:s ndarly in a lirie« 
And though it may be rather more remarkable, that this (hould 
happen with two compound iyftems, which are not by far {(y 
numerous as {ingle ftars, we have, to make up for ithis .^ngUr 
larity, a much larger fpace in which it may take . place, the 
clufter being of a very confiderable extent. " 

On the 15th of February, 1 786^ I difcovered (hat ptie of 
my planetary nebulae (c), had a fpot in the center, which was 
more luminous than the reft, and with long attention, a very 
bright, round, well defined' center becafne yiifible. IremaftB^d not: 
a iingle moment in doubt, but that the bright center was con* 
ne£led with the reft of the apparent dilk. 

In the year 1 7^5, the 6th of Oftober, I found a very bright^ 
round nebula, of about if minute in diameter (i/). It haa a 
large, bright nucleus in the middle, which is undoubtedly 



(a) RA. 7 3a 1. 


PD. X04 i^ 


(*) 7 3* S- 


104 15. 


(<r) 17 58 25. 


' 23 aa. 


(-/) 3 30 35. 


109 i5> 



coatieaed 



on Nebulwf Stars. 77 

conoeded with the luminous parts about It. And though we 
jnuft confefs, that if this phaenomenon, and many more of 
the fame nature, recorded in my catalogues of nebulae, confift 
of cluftcring ftars, we find ourfelves involved in fome difficulty 
to account for the extraordinary condenfation of then) about 
the center; yet the idea of a connexion between the outward 
parts and thefe very condenfed ones within is by no means 
leflened on that account. 

There is a telefcopic milky way, which I have traced out in 
the heavens in many fweeps made from the year 1783 to 
1789 (a). It takes up a fpace of more than 60 fquare degrees 
of the heavens, and there are thoufands of ftars fcattered over 
it : among others, four that form a trapezium, and are fituated 
in the well known nebula of Orion, which is included in the 
above extent. All thefe ftars, as well as the four I have men- 
tioned, I take to be intirely uncoimefted with the nebulofity 
which involves them in appearance. Among them is alfo 
.d Orionis, a cloudy ftar, improperly fo called by former aftro- 
nqmers ; but it does not feem to be conoe6ted with the milkinefs 
any more than the reft. 

I come now to fome other phaenomena, that, from their 
iingularity, merit undoubtedly a very full difcuffion. Among 
the reafons which induced us to embrace the opinion, that all 
very £aint milky nebulofity ought to be afcribed to an aftemblage 
of ftars is, that we could not eafily afilgn any other caufe of 
fuf&cient importance for fuch luminous appearances, to reach 
us at the immenfe diftance we muft fuppofe ourfelves to be 
from them^ But if an argument of confiderable force ftiould 
now be brought forward, to ftiew the exiftence of a luminous 
matter, in a ftate of modification very different from the con- 

(-1) RA. from 5 h. 15' 8" to 5 h. 39' 1'. PD* from 87^46' to 98° 10'. 
4 ftrudion 



•^8 2)r. Heuschel's O^erDations 

-flruftion of a fun or ftar, all objeftions, drawn from ouf 
Incapacrty of accounting for new phaemomena upon oH prin- 
ciples, will lofe their validity* 

Hitherto I have been fhewing, by varioas inftanccs in objects 
whofe places are given, in what manner we m^y form the ideas 
of connexion and its contrary by an attentive infpcflitaft of 
them only : I will now relate a feries of obfervations, with 
remarks upon them as they are delivered, from which I ffiaH 
afterwards draw a few fimple concltifions, that fecm to be of 
confidefable importance. 

To diftinguifli the obfervations from the remarks, the former 
are given in italics, and the date annexed ts that on which tbm- 
obrjeds were difcovered ; but the dcfcrrptions arc cxtraded 
from all the obfervations that have been made upon them. 

Odlober 1 6, 1784. A finr tif about the ^th magnitude^ fur- 
rounded by a milky nebulofity^ ar the^elure^ of about ^ tninutes tn 
diameter. Tbe nebulofity is very faint ^ and a little extended or ellip^ 
licaU the exteM being not far from the meridian^ of a Ht^le Jtcm 
north preceding to fouth following. The cbevelun inches a 
fmalljlar^ which is about if minute north rf the thmdy Jhri 
other Jlars of equal magnitude are peffe&fy free from ibis aippear^ 
4snce {a). 

My prefent judgement concerning this remarkable obje6fc \t^ 
that the nebulofity belongs to the fl:ar vrhich is iktrated in its ttti^ 
ter. The fmall one, on the contrary, which is mentioned as in- 
volved, being one of many that ar€ profufely fcattetcd over 
this rich neighbourhood, I fuppdfe to be quite unconneded 
with this phaenomenon. A circle of three minutes in diameter 
is' fufficiently large to admit anotber*fmaU (lar, without any 
bias to the judgement t form concerning the one in queffion, 

(«) RA.sh. S7'4". PD. 96^«'. 

It 



M Nihuloui Statu j^ 

It mufi appear fingular, thatfuch aii objed fhould not have 
unmediatciy fuggefied all the remarkis contained iti this Paper; 
but about things diat appear new we ought not to form opimous 
too haililjr^ and my obfervations oil the oonftrudkm of the 
heavens were then but entered upon. In this cafe^ therefore^ 
it was the fafeft way to lay down a rule not to reafon upon the 
phsttomeiia that might offer themfelyes, till I ihould be in 
pofleilion of a fufficient Aock of materials to guide my re« 
fearches* 

October 169 1784. A fmMU Jiar i>f about tbt wthcriztb^ 
magnJtuJe^ veryJuifUly afeSed with milky neiiUofity ; ether Jars 
of the fame magnitude are perfeSlly free fr^m this appearance. 
Another ofafervatko mentious 5 or ^fmidlfiars nvitl^n thefpace 
of ^or 4^^, all very faintly affetied in the fame manner^ ami the 
nebulofiiy fufpeSed t^hea little fir(mger about each Jiar. But a 
third obfenratioQ rather oppofes this increafe of the faintly 
Inminaus appearance {a). 

Here the connedioa between the ftars and the nebulofity i^ 
not io evident as to amount to convidioo { for which reafon 
we (hall pafs od to the next. 

January the 6tht 1785. A bright Jiar njoith a conjiderahle 
wiiky chevelure; a little extended^ 4 er 5^ in lengthy and near 4^ 
broad; it lo/es itfelf infenfibly. Other Jlars of equal magnitude 
are ferfeSlfy free from this, chevelure {b). 

The connedion between the ftar and the chevelure cannot 
be doubted, from the infenfible gradation of its luminous 
appearance, decreafing as it receded from the center. 



h. . a 



(tf) RA. 6 o 33. PD. 96 13. 

(*) S 30 S3- 9^ i»- 

January 



8o Dr. Herschel*s Ohfervatlons 

January 31, 1785, A pretty confiderable Jtar^ with a very 
faint y and very f mall ^ irregular^ tnilky chevelure ; other ftars of 
the fame Jize are perfectly free from fuch appearance (a). 

I can have no doubt of the connexion between the ftar and 
its chevelure. 

Odtober 5, 178*5. Aftarwlth a frong bur all around. A 
fccond obfervation calls it a very bright nucleus^ with a mlky 
nebulofity^ of no great extent. A third fufpefls the milkinefs to 
belong to more of thefame^ which is diffufed over the whole fioeep 
in that place ; but a fourth fays, that the milky nebulofty is much 
ftronger than what the nebulous grmmd, on which the Jlar h 
placed J in titles it to (i). 

The con'neftibn, therefore, between the nebulofit/ and the 
ilar is evident. 

January 1, 1786. A far furrounded with milky chevelure ; 
the far is not central. A fecond obfervation calls it affeSei 
with a very faints and extenfve^ milky chevelure. A third only 
mentions afar affeSted with milky chevelure (c). 

As by the word chevelure I always denoted fomething 
relating to a center, the connection cannot be doubted. 

February 24, 1786. Aconfiderablefar^ very faintly offeBed 
with milky chevelure. A fecond obfervation, much the 
fame {d). 

November 28, 1786. A far involved in milfy cbeve* 
lure (e). 





h. / ., 


/ 


(a) RA, 


, 6 54 a;. 


PD. icxj 53. 


(*) 


5 as 57- 


96 52. 


(') 


S 35 56. 


89 50. 


CO 


5 59 4. 


. 96 19. 


(0 


5 57 4- 


96 15. 



JaauarjT 



on Neiu/ous Stars. %t 

Januafy tjt 1787. j1 fiar with a pretty Jirong milky mbu^ 
h^y^ equally dijperjed all around -; the ftar is of about the gfh 
magnitude. A memorandum to tlie obfervation fays, that, 
having but juft begun, / Ju/peSled the glafi to be covered with 
dampy or the eye out of order i but yet ajiar of the \otb or i\ib 
magnitude J ju/l north of it^ was free from the fame appearance. 
A fecond obfervadon calls it one of the ntofi remarkable ph^no^ 
mena I ever have feen^ and like my northern planetary nebula 
in its growingfate (a). 

The connection between the ftar and the milky nebulolicy Is 
without all doubt. 

November 3, 1787. A bright ftar with faint nebuiofiiy. A 
iecond obfervation mentions thtjlar to be of the ^th magnitude^ 
and the faint nebulofity of very little extent (b). 

June IT, 1787. SufpeSledyJlellar. By a fecond obfervation 
it is verified, and called a very fmall ftar involved in extremely 
faint nebulofity [c). 

November 25, 1788. A fiar if about the (jith magnitude ^ 
furrounded with very faint milky nebulofity t other fiars of the 
famefize are perfeSlly free from that appearance. Jjefs than i^ in 
diameter. T!heftar is either not round or double (d). 

March 23, 1789. A bright^ con/ideraHy well defined nucleus^ 
vfitb a veryfainty fmall^ round cbevelure {e). 

The connexion admits of no doubt ; but the objed is not 
perhaps of the fame nature with thofe which I rail cloudy ftars» 



bv , , 




(«) RA. 7 16 28. 


FIX 6^ 39. 


(i) 43 11 26. 


30 0. 


(0 >7 > SI- 


47 a^ 


(i) I 57. 


18 41. 


(/) 11 la 25. 


50 i7» 


yoL.LXXXL 





M April 



82 Dr. Herschel*s Ohfsrvations 

. April 14, 1789. A confiderabUj bright^ rounJneiuIa; hav^ 
ing a large place in the middle of nearly an equal brigbtnefs^ but 
lefs bright towards the margin (d). 

This feems rather to approach to the planetary fort. 

March 5, 1 790. A pretty conjiderable Jiar of the f)tb or \otb 
magnitude^ vtfibly affeSied with very faint nebulofity of little 
extent^ all around. A power of 300 fhewed ^be nebulofty of 
greater extent (Ji). ' 

The connexion is not to be doubted. 

March 19, 1790. A very bright nucleus^ withafmall^ very 
faint chevelure^ exaSily round. In a low jituation^ where the 
cbevelure could hardly befeen^ this objeSl would put on the appear-' 
ance of an ilUdefined^ planetary nebida^ of 6^ 8, or lof^ diame* 
ter (r). 

November 1 3, 1 790. A moftjingular phanomenon ! Afiar of 
about the %ib magnitude^ with a faint luminous atmofphere^ of a 
circular form^ and of about ^ in diameter. 7he ftar is perfeS/y 
in the center^ and the atmofphere is fo diluted^ foint^ and equal 
throughout 9 that there can be no furmife. of its confjling of far s ; 
nor can there be a doubt of the evident connexion between theatmo* 
jphere and the Jiar. An:therjiar not much lefs in brightnefs^ and 
in the fame field with the above ^ was perfe^ly free from anyfucb 
appearance (^). 

This laft objeft is fo decifive in every particular, that we 
need not hefitate to admit it as a pattern,, from which we are 
anthorized to draw the following important confequences. 



"• / // 
(tf) RA. II 45 12. 


PD. 


/ 

33 43. 


(« 6 58 40- 




91 29. 


(f) 9 ay aa. 




30 11. 


(^ 3 56 48. 




59 50- 



Suppc^ng 



on Nebulous Stars. 83 

Stippofing the cotinedion between the Aar and its furround- 
ing nebulofity to be allowed, we argue, that one of the two 
following cafes muft neceflarily be admitted. In the firft place, 
if the nebulofity confift of ftars that are very remote, which 
appear nebulous on account of the fmall angles their mutual 
diftances fubtend at the eye, whereby they will not only, as 
it were, run into one another, but alfb appear extremely faint 
and diluted ; then, what mud be the enormous (ize of 
the central point, which outfhines all the reft in fo fuper- 
lative a degree as to admit of no comparifon ? In the next 
place, if the ftar be no bigger than common, how very fmall 
and comprefled muft be thofe other luminous points that are 
the occaiion of the nebulofity which furrounds the central 
one? As, by the former fuppoHtion, the luminous central 
point muft far exceed the ftandard of what we call a ftar, fo, 
in the latter, the fliining matter about the center will be much 
too fmall to come under the fame denomination ; we therefore 
either have a central body which is not a ftar, or have a ftar 
which is involved in a ftiining fluid, of a nature totally un- 
known to us. 

I can adopt no other fentiment than the latter, (ince the 
probability is certainly not for the exiftence of fo enormous a 
body as would be required to (hine like a ftar of the 8th mag- 
nitude, at a diftance fufficiently great to caufe a vaft iyftem of 
ftars to put on the appearance of a very diluted, milky nebu- 
lofity* 

But what a field of novelty is here opened to our concep- 
tions ! A fliining fluid, of a brightnefs fufficient to reach us 
from the remote regions of a ftar of the 8th, 9th, loth, i ith, 
or I ath magnitude, and of an extent fo coniiderable as to take 
^P 3> 4> 5> ^f ^ minutes in diameter ! Can we compare it to 

M 2 the 



8+ ^^- Herschbl^s Obfervations 

the corufcations of the eledrical fluid in the aurora boreaKs? 
Or to the more magnificent cone of the zodiacal light as we 
fee it in fpring or autumn? The latter, notwithftanding I 
have obferved it to reach at lead 90 degrees from the fun, is 
yet of fo little extent and brightnefs as probably not to be 
perceived even by the inhabitants of Saturn or the Georgian 
planet, and muft be utterly invifible at the remotenefs of the 
neareft fixed ftar. 

More extenfive views may be derived from this proof of the 
exiflence of a (hining matter. Perhaps it has been too haftily 
furmifed that all milky nebulofity, of which there is fo much 
in the heavens, is owing to ftarlight only. Thefe nebulous 
ftars may ferve as a clue to unravel other myfterious phaeno^ 
mena. If the (hining fluid that furrounds them is not fo eflea«- 
tially connected with thefe nebulous ftars but that it can alio 
exift without them, which feems to be fufiiciently probable, 
and will be examined hereafter, we may with great facility 
explain that very extenfive, telefcopic nebulofity, which, as I 
mentioned before, is expanded over more than fixty degrees of 
the heavens, about the conftellation of Orion ; a luminous 
matter accounting much better for it than cluftering ftars at a 
diftance. In this cafe we may alfo pretty nearly guefs at its 
fituation, which muft commence fomewhere about the range of 
the ftars of the 7th magnitude, or a little farther from us, and 
extend unequally in fome places perhaps to the regions of 
thofeof the 9th, loth, nth, and 12th. The foundation for 
this furmife is, that, not unlikely, fome of the ftars that hap« 
pen to be fituated in a more condenfed part of it, or that per^ 
haps by their own attraction draw together fome quantity of 
this fluid greater than what they are intitled to by their fitua* 
tion in it, will, of courfe, affume the appearance of cloudy 
2 ftars ; 



on Nebulous Stars. gj 

ftars; and many of thofe I have named are either in this (Ira- 
turn of luminous matter, or very near it. 

We have faid above, that in nebulous ftars the exiftence of 
the (hining fluid does not feem to be fo eflentially conne6ted 
with the central points that it might not alfo exid without 
them. For this opinion we may affign feveral reafons. One 
of them is the great refemblance between the chevelure of 
thefe flars and the diffufed extenfive nebuloiity mentioned 
before, which renders it highly probable that they are of the 
fame nature. Now, if this be admitted, the feparate exigence 
of the luminous matter, or its independance on a central 
ftar, is fully proved. We may alfo judge, very confidently^ 
that the light of this (hining fluid is no kind of reflexion from 
the ftar in the center; for, as we have already obferved, 
refleded light could never reach, us at the great diftance we are 
from fuch objeds. Beddes, how impenetrable would be an 
atmofphere of a fufficient denfity to refied fo great a quantity 
of light ? And yet we obferve, that the outward parts of the 
chevelure are nearly as bright as thofe that are clofe to the ftar ; 
fo that this, fuppofed atmofphere ought to give no obftructioti 
to the paflage of the central rays. If, therefore, this matter 
is felf^luminous, it (eems more fit to produce a ftar by it^ 
condeniation than to depend on the ftar for its exiftence. 

Many other diffufed nebulofities, befides that about the 
conftellation of Orion, have been, obferved or fufpefted ; but 
fbme of them are probably very diftant, and run out far into 
fpace. For inftance, about 5 minutes in time preceding £ 
Cygni, I fufpe£k as much of it as covers near four fquare 
degrees ; and much about the fame quantity 44^ preceding the 
125 Tauri. A fpace of almoft- 8 fquare degrees, 6^ preceding 
« Triaogulii fcems to be tinged, with milky nebulofity. Three 

minutes. 



i6 Dr. Herschel^s Obfervationt 

minutes preceding the 46 Eridani, ilrong, milky nebuloiitjr 19 
expanded over more than two fquare degrees. 54' preceding 
the 13th Canum venaticorum, and, again 48^ preceding the 
fame ftar, I found the field of view afie£led with whitiffi. 
nebulofiry throughout the whole breadth of the fweep, which 
was 2° 39'. 4^ following the 57 Cygni, a confiderable fpace 
is filled with faint, milky nebulofity, which is pretty bright in 
fome places, and contains the 37th nebula of my Vth clafs, in 
the brighteft part of it. In the neighbourhood of the 44th 
Pifcium, vtty faint nebulofity appears to be diffufed over more 
than 9 fquare degrees of the heavens. Now, all thcfe phx- 
nomena, as we have already feen, will admit of a much 
eafier explanation by a luminous fluid than by {tars at an 
immenfe diftance. 

The nature of planetary nebulas, which has hitherto been 
involved in much darkiiefs, may now be explained with fome 
degree of fatisfaflion, fince the uniform and very confiderable 
brightnefs of their apparent difk accords remarkably well with 
a much condenfed^ luminous fluid ; whereas to fuppofe them 
to confift of cluttering ftars will not fo Completely account for 
the milkinefs or foft tint of their light, to produce which it 
would be required that the condenfation of the fiars (hould be 
carried to an almoA inconceivable degree of accumulation* 
The furmife 6f the regeneration of ftarsi by means of pla* 
netary nebulae, exprefled in a former Paper, will become more 
probable, as all the luminous matter contained in one of themi 
when gathered together into a body of the fixe of a ftar, would 
have nearly fuch a quantity of light as we find the planetary 
nebulae to give. To prove this experimentally, we may view 
them with a telefcope that does not magnify fufficiently to 
(hew their extent^ by which means we fliall gather all their 

light 



6n Nebuldus Stars. 87 

Jight together iato a pornt, when they will be found to affume 
the appearance of fmall ilars ; that is, of ftars at the dillance 
of thofe which we call of the 8th, 9th, or loth magnitude. 
Indeed this idea is greatly fupported by the difcovery of a well 
defined, lucid point, refembling a flar, in the center of one of 
them : for the argument which has been ufed, in the cafe of 
nebulous flars, to (hew the probability of the exiftence of a 
luminous matter, which reded upon the difparity between a 
bright point and its furrounding (hining fluid, may here be 
alledged with equal judice. If the point be a generating ftar, 
the further accumulation of the already much coudenfed, 
luminous matt^r^ may complete it in time. 

How far the light that is perpetually emitted from millions 
of funs may be concerned in this (hining fluid, it might be 
prefumptuous to attempt to determine ; but, notwithftanding 
the unconceivable fubtilty of the particles of light, when the 
number of the emitting bodies is almod infinitely great, and 
the time of the continual emKfion indefinitely long, the quan- 
tity of emitted particles may well become adequate to the con- 
ftitution of a (hining fluid, or luminous matter, provided a 
cau(e can be found that may retain them from flying off, or 
reunite them. But fuch a caufe cannot be difficult to guefs at, 
when we know that light is fo eafily reflefted, refrafted, in- 
flected, and defleded ; and that, in the immenfe range of its 
courfe, it muft pafs through innumerable (yftems, where it 
cannot but frequently meet with many obffacles to its refti- 
linear progreffion. Not to mention the great counteradlion of 
the united attradive force of whole (idereal (yftems, which 
muft be continually exerting their power upon the particles 
while they are endeavouring to fly off. However, we (hall lay 
no firefs upon a furmife of this kind, as the means of veri- 
I fying 



2% Dr. Hbrschsl's Obfervations^ ice. 

fying It are wanting : nor is it of any immediate confequence 
to us to know the origin of the luminous matter. Let it fuf« 
fice, that its exiftence is rendered evident, by means of nebu- 
lous (lars* 

I hope it will be found, that in what has been faid I have 
not launched out into hypothetical reafonings ; and that hSts 
h«ve all along been kept fufficiently in view. But, in order to 
give every one a fair opportunity to follow me in the refledkions 
J have been led into, the place of every objeft from which I 
b.ive argued has been purpofely added, that the validity of 
what I have advanced might be put to the proof by thofe who 
are inclined, and furnilhed, with the neceflary inftruments to 
undertake an attentive and repeated infpedioa of the fame 
phiienoinena* 

W. HERSCHEL. 

«l(High, Jan. I, 1791. 




>>^>^. 



[ 8> ) 



V. AhjiraSt of a Regijler of the Barometer^ l^hertnomC'- 
ter^ and Rain, at Lyndon in Rutland ; iy Thomas Barker, 
Efq. ; with the Rain in Hampfliire and Surrey ; for the Tear 
17B9. Communicated l?y Thomas White, JS/j'. F.R.S. 

Read Feb. 17, 179 1. 



Barometer. 



Thermometer. 



Rain- 



la the Houfc. 



Hiffheft Loweft. 



Mean, 



HiglklLow. 



Mean 



Abroad. 
Hig^. Low. Mean 



Lyndon 



Surrey* 

S.Lam' 

bcth. 



Hampfljire, 



Scl. 
bourn* 



Fyftcid. 



to. 



HIT. 



Ipr. 



flay 



Dne 



ulv 



a. 



OV. 



Morn. 

Aftcrn. 

Mom, 

Aftcrn. 

Morn, 

Aftern. 

Morn. 

Aftem. 

Morn. 

Aftcrn. 

Morn, 

Aftcrn. 

Morn. 

Aftcrn. 

Morn. 

Aftcrn. 

Morn. 

Aftcrn. 

Morn. 

Aftcrn. 

M«rn. 

Afpcm. 

Morn. 

Aftcrn. 



Inches. 
30.25 

29>79 
29,67 

29,70 
29,80 
29,82 

29>63 
29,90 
29,88 
29,84 
29,90 
30,04 



Inches. 
28,00 

28,13 

28,50 

28,61 

29,12 

28,92 

29,10 

29,25 

a8,85 

28,52 

28,25 

28,3s 



laches. 
29>23 

29,18 

29,28 

29,42 

29.38 

29.39 
29,61 

29,40 

29,22 

29,26 

29.32 



47 

soi 

47i 

47i 

4oi 

40J 

53l 

SH 

63 

631 

64 

66 

63! 
65 

tl 

63 

64 

SSi 

57 

44 

ti 

48f 



«7 

28 

37i 

39 

34I 

36 

39i 

4ii 

48 

49 

53§ 

55 

56I 

58i 

55 

59i 

52i 

53i 

43i 

f 

37i 
381 



36 
37 
42 
43 

46 

48 

55I 

57 

58 

59 

6oi 

61I 

62 

63i 

57t 

59 

50 

51 

42 

42 

43 

44 



47 

5ii 

37 

46i 

5« 

67 

59 

6?.i 
62i 

74i 

571 

72 

50 

62 

43 

501 

5°! 

52i 



131 

2li 

3> 

36§ 

22 

33 
32 
43 
42I 

45I 

49 

58 

49i 

59i 

6oi 
42 
55 
32 

3Pi 

3°i 
34i 



32 
37 
37 
44 

3^ 

40 

4' 
S3 
50 

63* 

53 

67 

57 
69 

57 
69 

5oi 

(^3 

44 

52 

3H 

43 

40 

44 



Inch. 
2,604 

1,847 

1,152 
1,010 

1,677 

4,447 

4,259 

a.33V 
2,846 

4,93' 
1,199 

1,699 






Inches 28,002 



Inch. 
2.41 

2,5' 
3,32 
1,24 
3,So 

3>77 
i,9> 
1,87 
3-54 

1.5' 



Inch, 
4,48 

4»H 

2,47 
1,81 

4.05 
4.24 
3.69 
0,99 
2,82 
5.04 
3.67 
4>63 



42,00 35,61 



Inch. 
2,98 

2,3° 

1,58 

4.03 

5^°3 

3.9s 

0.33 

3.58 

3.35 
1,69 

3.48 
1 



Vol. LXXXI. 



N 



MANY 



90 Mr. Barker's Regifter of the 

MANY liave thought, that a hard winter generally comes 
after a w©t fummer, when the ground has been chilled with 
cold and rain ; fo the great froft in 1740 came after a cold wet 
fummer 1739 ; but it was not fo in 1788, which was in ge- 
neral a dry fummer, and in fome places very much fo, and 
not defedtive in hot weather. The whole year's rain was 17 
inches, which is lefs than any year (ince 1750. The autumn 
was dry and fine, and fo free from frofts, that feveral au- 
tumnal flowers were flowering in the garden when the froft 
began, which are often cut oS a month or more earlier. 

The laft day I have Mentioned as mild was Nov. 22. and 
the firft day of the froft Nov, 26 ; it began in Hampfhire 
three day^ fooner. But for more than the firft fortnight it was 
very moderate, often freezing at night and thawing in the day ; 
and it began to be fevere Dec. 12.; was exceeding cold, and 
fome very ftiarp winds, and, as there was then no confiderable 
fnow, it entered deep into the ground. An imperfed: thaw,^ 
Dec. 24. and 25. was fdlowed by a great fnow, and the froft 
returned as hard as ever. There came fnow again feveral 
times ; and it lay fo loofe and hard frozen on the ground, as 
to be often driving about into very gi-eat heaps; till January 13^ 
1789, when, in one pf the worft days of all for ftorm, fnow, 
and driving, it began to thaw at night ; yet the ground was io 
hard frozen and cold, efpecially where J)aths had been fwept, 
that the moifture of the air continued freezing for fome days 
longer in cakes of ice on the bare ground and ftones. 

It was remarkable that this froft was feverer fouthward than 
northward, in France than England. ' It froze over our great 
rivers^ yet not fo as to venture ^ build oa them, as was done 

in 



WtathtT at Lyiwion in Ratland, 91- 

in 1740. It alfo froze the much larger rivers of Europe, tind 
was in moft parts a fevere winter; but to the north and north- 
weft of us, it appears not to have been fo, and that it was 
oioderate in Scotland, and was chiefly great fnows in Ireland. 

The air was very (harp during the froft, and it froze ex- 
ceeding hard, even withm doors ; yet I have feen the thermo- 
Boeter lower in other frofts than it was in this. The loweft I 
fsw was Jan. 12. at ij^i ; but in Jan. 1786, it was down at 
ii**! ; in the fevere froft Jan. 1776, it was 11^ and 10®; 
Feb. 1784, at 9°; Dec. 1783, at S^^f ; and one morning, 
Feb. 12, 1 771* it was down at 4% which is the loweft I ever 
iaw it. 

The froft from Dec. 1739 to Feb. 1740 was the greateft I 
ever knew, and many trees, Ihrubs, and plants, were killed 
by it, or nearly fo ; but in general they efcaped this winter. 
In mofft gardens every plant of rofemary was killed that year, 
few or none were much hurt this winter. In 1740, the ^vheat 
in many countries received great damage ; m this froft I be* 
lieve it was very little hurt. Moft of the branches of com- 
mon furze were killed in 1740, many quite down to the; 
ground, and fome were entirely deftroyed ; and I have known 
many fufier much, and fonK killed, in 1776, and other hard 
winters ; but this year only a few were much hurt. Many 
turaeps were frozen in the fields this year, a hufliandry not io 
much praftifed in 1740; and many apples and pears were 
ftozen in the houie, where they were not carefully prcferved ; 
yet, I think, there was lefs of this than was apprehended. 
Artichokes, I think, fufFered as much as moft things in the 
garden; fome were killed, and others fo hurt as to prevent 
their bearing, but many efcaped ; but there was a greater lofs 
among them in i740» 

N a Many 



gz Mr. Barkbr^s Regtfifir 0/ the^ 

, Many walnut-trees were fplit from the collar to the root bj 
the great frofl m 1740, fo that a knife might he thruft ia 
eight or ten inches i the clefts clofed again in fummer, bub 
never united. They grew out into a feam higher than thc^ 
reft of the wood, and have fo continued ever fince, yet with- 
out hurt either to the growth or bearing of the trees, anA 
feveral of them were again fpllt by the late froft. Such fcams. 
may be feen on many wajlnut-trees 'where the caufe is not 
remembered. It feenis odd, that clefts which did i>ot affed^ 
the growth of a trfee (hould yet never heal, but remain an inde- 
lible mark for fo long a time; but it feems to me, that if 
wood is once parted, it will never join again, for the wholcr 
growth of a tree is between the bark and the wood ; but 
the cleft may be covered over with new wood, as wc fome- 
times fee a branch broken off when the tree is young covered 
over with a great thicknefs of timber. 1 have known feveral 
afli trees fplit by lightning without a twig being killed ; but,, 
ill feveral years they ftood afterward, there were no figns of 
their uniting again. In an oak, which had fome bark ft ruck 
off by the fame means laft year, but is not iplit that I kqow 
of, fortie of the lefler branches withered* 

One thuig feems to have been more common this ye^r than 
In 1740, and tliat was the lofs of fiih in ponds. Where: 
t;he ponds were deep, well fupplied with water, and the ice 
unbroken, no fifli died; but where the water was fliallow, 
little or no current, and the ijce kept broken, many periflied ; 
and in fome places, where all.thefe caufes concurred, they 
were, all killed. The difference might arife from the want of ^ 
water thi?year after a dry autumn, of which there was no defefl: 
Ln 1 739*. Carp were taken out of a pond where th^ ice was 
broken, frozen crooked and ftiff without the Icaft motion, and 

ice: 



Weather at Lyndon in Rutland. ^3 

ice banging about them; but, being laid on dry flraw in vL 
cellar, they all recovered* Some have made a practice of 
breaking the ice to give the fi(h air ; but, by all the examples 
I heard of in this froft, it appears to be a great miflake, and 
that they are much fafer without it* 

Times of diftrefs will make creatures look out for unufual 
food. A land animal does not feem naturally to live on fifh ; 
but in this froft a fox was frequently tracked to the mouth of 
a covered drain, juft deep enough to let in the fifti from a pond, 
and was one morning feen eating one on the bank, the blood of 
which was traced on the fnow to the drain, fhewing plainly 
that it came from thence. 

After the froft broke it was windy and wet, and the air did 
not become mild for ten days or a fortnight ; and the ground 
was fo dry within, that the melting of the fnow and the rain 
together did not make great floods. It continued often windy 
and (howery till March ; but from the latter end of January 
it was, as towarmth, mild. With March the winter returned, 
there was almoft conftant north winds, frofty mornings or quite 
froft, and fooaetimes hard and frequent fnow. This flopped 
the feed time, which was begun before, and made it late ; but 
when it did come, it was good. The fpring was backward, 
and frequent frofty mornings; but mended gradually, and 
things came on, though flowly, and the fpring wa3 dry till the 
middle of May. 

Then came a (howery and fine growing time for three weeks, 
and after a fhort time it became hot and dry.. The middleof June 
a wet feafon began with a v6ry great rain, aiid it was wet without 
interruption till the end of July. There was a great deal of hay- 
made this year, but little of it right good. Many of the mea- 
dows were flooded ; the uplands could not be well gotten for 
3 the 



94 Mir. Barker's Regjftir^ &c. 

the wet ; there were great oddiflies, and a vaft deal of late 
grafs, much of which was well made into hay in Auguft, 
which was a fine dry fummer mpnth; but fuch late grafs is 
not fo good as the earlier. This nuxith was rather an interrup- 
tion than a ceaiing of the wet feafon, which began again the be- 
ginning of September, and continiaed to the cadi of the year, 
but the rain fell in lefs quantity from the middle of Oftober to 
the middle of December; but the feaibn has been very opeti 
and mild, icarcdy any froft, and the ground Aill green at 
Chriftmas. 

The .fummer was fo wet there was vtry little honey this 
year. The growth of trees was very great ; many (hoots were 
three and four feet long or more ; and a young aih tree, of fix 
feet h^h, in the garden, made a (hoot five feet and an half 
long, and as thick as a finger. The grain was very rank and 
foul; there was bulk enough upon the ground, but it yielded 
very badly to the threfher, perhaps not greatly amifs to the 
acre. Harvefl being late, but little was got in during the fine 
month of Auguft: the white corn was however carried* in 
tolerable order ; but a great many of the beans and peafe 
were fpoiled. 




\ 



[ w J 



VI. QbJervAtions ra ctrtaim b^rny Excnfances of the Human 
Body. By Everard Home, Efq. F. R. SL 

Read February 1 7, 1791. 

THE biftory of difeafes belongs not properly to the pro- 
vince of the naturalid or phiiofopher; it is intimately 
GOQoe^ted with the inquiries of the phyfician and anatomiil ; 
but when difeafe becomes a cauie of the formation of parts 
fioular to others exifiing in nature^ but rendered uncommon by 
novelty of iituatioa, or produced in aniaials to which they are 
not naturally appropriated^ it may be cdnfidered as having in« 
ftituted a monftrous variety, highly deferving of attention from 
the naturalift. 

To defcribe fuch varieties is indeed more fully the ofiice of 
natural hiftory than of medicine ; but the invefiigation of dif- 
eafes which are found to fubvert the ordinary laws of nature 
r^fpeding the fituation or produ6ki€)o of parts in an animal 
body, undoubtedly belongs to the medical practitioner. 

By thefe confiderations I have beeo induced to lay before the 
Royal Society the following account of a difeafe which occurs 
fometimes in the human body, very remarkable in its cfFefls, 
but very little underilood as to its caufe ; namely, the pro- 
dudkion of an excrefccnce fimilar to,a horn. So curious a ph9?« 
Bomenon has naturally altraded the attention of the ignorant 
as well as the philoibphieff ; and the indayudoals who have had 
the misfortune to be iubjed to this difeafe have been conddered 
as inonfters. 

Homy cxcrefcenoes arifing from the human head have not 

OQly.occttirred in this couatiy, but have faeea met with in fe* 

I ' veral 



5 6 Mr. HoyiE^sObferoatiom on 

veral other parts of Europe ; and the horns themfclves have been 
depofited as valuable curiofities in the firfl colledions in Europe. 

In giving the hiftory of a difeafe fo* rare in its occurrence, 
and in its efFeds fo remarkable as almofl: to exceed belief, it 
might be thought right to take fome pains in bringing proofs to 
afcertain that fuch a difeafe does really exift : I confidcr the 
doing fo as lefs neceffary at prefent, there being two women 
flow alive, and refiding in England, who are afFefted by the 
complaint. I fliall, however, in the courfc of this Paper, 
bring other evidence from the teftimony of the moft re(pe£tabl6 
authors who have confidered this fubjed. 

The two following cafes contain a very accurate and didin^ 
hiftory of the progrefs of the difeafe through its different ftages, 
and make any further detail of the iymptoms intirely unne- 
ceflary. 

Mrs. lloNSDALB, a woman ^6 years old, a native of Horn- 
t:aftle in Lincolnftiire, fourteen years ago, obfe/ved a moveable 
tumor on the left fide of her head, about two inches above the 
upper arch of the left car, which gradually increafed in the 
courfe of four or five years to the fize of .a pullet's egg, when it 
burft, and for a week continued to difcharge a thick, gritty 
fluid. In the center of the tumor, after the fluid was dif- 
charged, fhe perceived a fmall foft fubftance, of the fize of a 
pea, and of a reddifti colour on the top, which at that time (he 
took for proud flefh. It gradually increafed in length and 
thicknefs, and continued pliable for about three months, wl%en 
it firft began to put on a horny appearance. In two years and 
three months from its firft formation, made defperate by the 
increafed violence of the pain, fhe attempted to tear it from her 
head ; and with much difficulty, and many efforts, at length 
broke it in the middle, and afterwards tore the root from her 
head, leaving a confiderable deprefilion which ftill remains in 

the 



Hor^ Excrefcenccs of the Human Body. ^y 

the part where it grew. Its length altogether is about five 
inches, and its circumference at the two ends about one inch ; 
but in the middle rather lefs. «It is curled like a ram's horn 
contorted, and in colour much refembling iiinglafs. 

From the lower edge of the deprefiiou another horn is now 
growing, of the fame colour with the former, in length about 
three inches, and nearly the thicknefs of a fmall goofe quill ; 
it is lefs contorted, and lies clofe upon the head. 

A third horn, iituated about the upper part of the lambdoidal 
future, is much curved, above an inch in length, atid more in 
circumference at its root : its diredion is backwards, with fome 
elevation from the head. At this place two or three fucceilive 
horns have been produced, which (he has ccMiftantly tora 
away; but, as frefli ones have fpeedily followed, (he leaves the 
prefent one unmolefted in hopes of its dropping off. 

Beiides thefe horny excrefcences, there are two tumors, each 
the iize of a large cockle ; one upon the upper part, the other 
about the middle of the left (ide of the head ; both of them 
admit of confiderable motion, and feem to contain fluids of un- 
equal coniiftence ; the upper one affording an obfcure fludtua- 
tion, the other a very evident one. 

The four horns were all preceded by the fame kind of in« 
cyfted tumours, and the fluid in all of them was gritty; the 
openings from which the matter iflued were very fmall, the 
cy(ls coUapfed and dried up, leaving the fubftance from which 
the horn proceeded di{tingui(hable at the bottom. Thefe cyfts 
gave little pain till the horns began to (hoot, and then became 
very diflrefling, and continued with (hort intervals till they 
were removed. This cafe is drawn up by the furgeon who 
attended the woman for many years, which gave him frequent 

VoL.LXXXI. O oppor. 



^$ Mr. Homers Objervatloni on 

opportunities of feeing the difeafe in its .di^rent ftages, andl 

acquiring an accurate hiftory of its fymptoms, 

Mrs. Allen, a middle-aged woman, refident in Leiceftcr-* 
(hire, had an incyftcd tumor upon her head, immediately under 
the fcalp, very moveable, and evidently containing 4 fluid. 
It gave no pain uulefs preiTed upon, and grew to the fize of a 
fouiU hen's egg. A few years ago it buril, and djfcharged a 
fluid ; this dimiaiihed in quantity, and in a fliort time a horny, 
eicrefcence, fimilar to thofe above mentioned, grew out from 
the orifice, which has continued to increafe in fize ; and in the 
month of November 1 790, the time I faw it, was about five 
inches long, and a little more than an inch in circumference at 
its bafe. It was a good de<il contorted, and the furface very 
irregular, having a laminated appearance. It nioved readily 
with the fcalp, and feemed to give no pain upon motion ; but» 
when much handled, the furrounding ikiu became inflamed. 
This woman came to London, and exhibited herfelf as a (how. 
for money ; and it is highly probable, that fo rare an occur- . 
rence would have fufliciently excited the public attention to 
have made it anfwer her expeflations in point of emolument, 
had not the circumflance been made known to her neighbours 
in the country, who were much diflatisfied with the meafure, 
and by their importuijity obliged her hulband to take her into 
the country. 

V That the cafes which I have related may not be confidcred as 
peculiar inflances from which no conclufions can be drawn, it 
may not be amifs to take notice of fome of the moA remarkable 
hiflories of this kind, mentioned by authors, and f^e how far 
they agree with thofe I have ftated*, in the general charadlers 
that are fufliciently obvious, to ftrike a common obferver ; for . 
the vague and indefinite tern^in which authors exprefs thegi- 

felves 



Horny Excrefcences of the Human Body, 9^ 

ftlves on tht$ fubje£t (hew plainly, that they did not undefr* 
ftand the nature of the difeafe, and their accounts of it are not 
very fatisfaftory to their readers. 

In the Ephemerides Academta Naturae Cunofornm there are twci 
cafes of horns growing from the human body. One of thefe in»- 
ftances was a German woman *, who had feveral fwellings, or 
ganglions^ upon different parts of her head, from one of 
which a horn grew. The other was a nobleman f , who had a 
fmali tumor, about the (ize of a nut, growing upon the parti 
covering the two laft or lowermoft vertebrae of the back, ft 
continued for ten years, without undergoing any apparent 
change ; but afterwards enlarged in fize, and a horny excref- 
ceilce grew out from it. 

In the Hiftory of the Royal Society of Medicine J, there is 
an account of ,a woman, 97 years old, who had feveral tu- 
mors on her head, which had been 14 years in growing to the 
ftate they were in at that time : (he had alfo a horn which had 
originated from a (imilar tumor. The horn was very move- 
able, being attached to the fcalp, without any adhefion to the 
fcuU. • It was fawn off, but grew again, and although the ope-^ 
ration was repeated feveral times, the horn always returned. 

Bartholine, in his Epiftles§» takes notice of a woman' 
who had a tumor under the fcalp, covering the temporal 
mufcle. This gradually enlarged, and a horn grew from it, 
which had become twelve inches long ^^^ the year 1646, the 
time he faw it. He gives us a reprefentation of it^ which bears, 
a very accurate refemblance to that which I have mentioned 
to have feen in November 1790* No tumor or fweliing is 

* Ephem. Acad. Nat. Cur. Dec. iiL An. V. Append, p. 148. 
t Ibid. Dec. i. An. I. Obfervat. 30. 

X Hifioire de la Societe Royale de Medecine, 1 776, p. 316. 
§ Epifiol. Thom. Baethol. 

O 2 exprefled 



loo Mr. HoMuhOi^f^Mions on 

expreffed in t)ie figure ; but the horn is coming direAly o\ie 

from the furface of the (kin. 

In the Natural Hiftory of Chefhirc *, a woman is men- 
tioned to have lived in the year 1668, who had a tumor or 
wen upon her head for 32 years, which, afterwards enlarged, 
and two horns grew out of it ; Ihe was then 72 years old. 

There is a hprny excrefcence in the Britifh Mufeum, which 
is eleven inches long, and two inches and a half in circum- 
ference at the bafe, or thickeft part. The following account 
of this horn I have been favoured with by Dr. Gray, taken 
from the records of the Mufeum. A woman, named French, 
who lived near Tenterden, had a tumor or wen upon her head, 
which increafed to the fize of a walnut ; and in the 48th year of 
her age this horn began to grow, and in four years arrived at 
its prefent fize +. 

There are many fimilar hiftories of thefe horny excrefcences 
in the authors I have quoted, and in feveral others j but thole 
mentioned above are the moft accurate and particular with 
refpeft to their growth, and in all of them we find the origin was 
from a tumor, as in the two cafes I have related ; and although 
the nature of the tumor is not particularly mentioned, there 
can be no doubt t)f its being of the incyfted kind, fince in its 

* Lee*9 Natural Hiftory of Lancaftiirc and Chcfhirc, 

+ The fbH6wing cxtraft is taken from the Minutes of the Royal Society, Feb. 
14, 1704.5. 

•« A Letter was read from Dr. CHAtiERE, at Barnftaple, concerning a horn, . 
«* fcvcn inches long, cut oflf the iecood vertebra of the neck of a woman in that 
** neighbourhood. 

*« Dr. Gregory faid, that one of fevcn inches long, and of a dark brown 
*« colour, was cut off from a woman*s temple at Edinburgh. 

*• Dr. NoRRis-'iaid, thit Wo honts had been cut off from a woman's licad 
*« in Chcfliife. ' j . 

progrefs 



Horny Excrefeimces cf tire Human Botfy^ lof 

progrefs it exadly refembled them, remainiog fhtionaiy for a 
long timey and then coming forwards to the Ikin ; and the 
horn being much fmaller than the tumor previoufly to the for- 
mation of the horn, is a proof that the tumor muft have burft, 
and difcharged its contents* 

From the foregoing account it muft appear evident, that 
thefe horny excrefcences are not to be ranked among the ap* 
pearances called lufus nature : nor are they altogether the pro- 
duA of difeafe, although undoubtedly the confcquence of a 
local difeafe haviiig previoufly exifted ; they are, more properly 
fpeaking, the refult of certain operations in the part for its own 
reftpration ; but the actions of the animal oeconomy.; being 
unable to bring them back to their original ilate, this fpecies 
of excrefcence is formed as a fubfiitute Sot the natural cuticu^ 
lar covering. 

To explain the manner in which thefe horns are formed, it 
will be neceflary to confider the nature of iucyfted tumors a 
little more fully ; and in doing fo we fliall find, that this par- 
ticular fpecies does not differ in its principle, nor materially in 
its effects, from many others which are not uncommonly met 
with ill the human body, as well as in thofe of many other 
animals, which, as they are more frequent in their occurrence, 
are alfo much better underflood. 

Incyfled tumors differ exceedingly among themfelves^ both 
iu the nature of their contents, atid in their progrefs towards the 
external furface of the body. Many of them have no reference 
toourprefent purpofe; it is only the more indolent kind to- 
which I mean now to advert v: feme of thefe^ when examined^ 
nre not found to contain a fluid, but a fmall quantity of thick, 
c.urd-like matter, mixed with cuticle broken down into fmall 
p^arts, and upon expoftng the internal furface of the eyft, it is 

found 



ionn^ to htve an' tmifbrm^uticular covering adhering to Itf {imU 
W to chaft of the cutis on the furfaec of the bodj, from which 
it only differs in being th inner, and more delicate, bearing a. 
greater, rcfemblance to that which covers the lips. Others of 
this kind, indead of having cuticle for their contents, are filled 
with hair mixed with a curdled fafaftance, or hair without any 
adcnixturc whatever, and have a 6nailar kind of hair growing upon 
their internal fur£aK:e, which is likewife covered with a cuticle^ 
Thcfe cuticular incyfted tumors were, I believe, firft accurately 
examined by Mr. Huntbr, to whom we are likewife indebted 
for an explanation of the mode in which the parts acquire this 
particular ftrudure. 

Mr, llvvvaL confiders the internal furface of the cyft to 
be lb circumftanced refpe^ting the body, as to lofe the ili* 
mulus of being an internal part, and receive the fame iav^ 
predion from its contents, either from their nature, or the 
length of application, as the furface of the fkin does from its 
external fituation. It therefore takes on anions fuited to fuch 
ilimuli, undergoes a change in its ftrudure, and acquires a dif- 
portion fimilar to the cutis, and is confequently pofTefled of 
the power of producing cuticle and hair. What the mode of 
action is, by which this change is brought about, is not eafily 
determined ; but from the indolence of thefe complaints, ic 
moft probably requires a coniiderable length of time to produce 
it. That the lining of the cyft really does poflefs powers fimi- 
lar to cutis, is proved by the following circumftances : that it 
has a power of forming a fucceflion of cuticles like the com- 
mon fkin ; and what is thrown off in this way is found in the 
cavity of the cyft. It has a fimilar power refpe6ling hair, and 
Sometimes the cavity is filled with it, fo great a quantity has 
been fhed by the internal furface^ Befides thefe circumftances> » 
2 the 



. Horny Exenfcmces of the HumM Body. n)^ 

the hair fouhd in the cjft corrcfponds in appearanca^ with that 
which grows upon the body of the animal ; and when Inqrfted tu- 
mors of this kind form in (heep, they contain wool. What is Aill 
more curious, when fuch cyfts are laid open, the internal fur^^ 
fsce undergoes no change from expofure, the cut edges cica«- 
trize, and the bottom of rhel)ag remains ever after an external 
furface. Difierent fpecimens, illuftrative of the above- men* 
tinned circumftances, are preferved in Mr. Hunter's collec- 
tion of di(eafes* 

The cyfls that produce horny excrefcences (which are only 
another modificatbn of cuticle) are very improperly . con(idered 
as giving rife to horns ; for if we examine the mode in which. 
this fubftance grows, we (hall find it the fame with the human, 
nails, coming directly out from the furface of the cutis. It 
differs from the nails in not being fet upon the fkin by a thin 
edge, but by a furface of fome breadth, with a hollow in the 
middle, exadly in the fame manner as the horn of the rhino- 
ceros * ; at leaft this is evidently the cafe in the fpecimeh pre- 
ferved in the Britiih Mufeum, and in one which grew out from: 
the tip of a fheep's ear; they are alfo folid, or nearly fo, in^ 
their fubfhnce. 

• This mode of growth is very different from that of horns, 
which are all formed upon a core, either of bone or foft parts, 
by which mean$ they have a cavity in them ; a ftrufture pecu- 
liar to this kind of cuticular fubflance. 

Incyfted tumors in different animals would appear, from 
tbefe obfervations, to be confined in their produflion to the 

♦ The horn of the Rhinoceros is a cuticular appendage to the ikin, fimilarto 

nails and other cuticular excrefcences, being in no refpcft allied to horns but in 

the external appearance. 

cuticular 



^04 ^^* HoMB^s Ohfervathns on 

cuticular fubftance proper to the animal in which they take 
place; for, although cuticle, hair, nail, hoof, and horn, are 
equally produdions of animal fubftance, only differing in tri-^ 
vial circumftances from each other, we do not find in the 
human fubjedt any inftance of an incyfted tumor containing a 
iubflance different from the cuticle, hair, and nails of the 
human body, to which laft the homy excrefcences, the fub-' 
jeft of the prefent Paper, are certainly very clofely allied, both 
in growth, flrudlure, and external appearance ; and when of 
foine length, they are found to be fb brittle as to break in two» 
upon being roughly handled, which could not happen either to 
hoof or horn. In the (heep they produce wool inftead of hair ; 
and in one inftance in that animal, where they gave rife to an 
horny excrefcence, it was lefs compad in its texture, and lefs 
brittle than fimilar appearances in the human fubjed: ; upon 
being divided ' longitudinally, the cut furface had more the ap- 
pearance of hoof, and was more varied in its colour than nail. 

Incyfted tumors being capable of producing horns, upon 
the principle we have laid down, is contrary to the ufual 
operations of nature ; for horns are not a production from 
the cutis, and although not always formed upon a bony* 
core, but frequently upon a foft pulp, that fubftance difiers 
from common cutis in its appearance, and extends a confidera-* 
way into the horn : it is probable, that this pulp requires a 
particular procefs for its formation *. 

^ A fliecp, about four years old, had a large horn, three feet long, growing 
upon its flank. It had no connection with bone, and appeared to be only attached 
to the external ikin. It dropped off in confequence of its weight having produced 
ulceration in the foft parts to which it adhered. Upon examining it there was 
a flelby fubftance^ fcven inches long, of a fibrous texture filling up its cavity 
upon which the horn had been formed. 

3 IfliaU 



Horny Excrefcenees of the Human Body. 105 

I (hall conclude this Pa|)er by obfervingt that the cafes of 
horns, as they lire commonly termed, upon the human bead^ 
are no more than cuticular produftions arifing from a cj(f, 
which in its nature is a variety of thoCe tumors defer i bed by 
Mr/ HuKTBR under the general name of cuticular incyfted 
tumorff*. 

Thefe incyfted tumors, when ^onfidered as varieties of the 
fame difeafe, form a very complete and beautiful .feries of the 
different oxxles by which the powers of the animal ceconomy 
produce a fubftitute for the common cuticle upon parts which 
have been fo much affeded hy difeafe ai to be unable to reftore 
themfelves to a iiatural ftate. 

"^ The ^inciple upon which the produdion of thefe excrefceaces depends 
being once explained, the modes of prevcndng their formationy and removing 
them wheti forknedy will be readily underflood, the deftruftion of the cyft bein^ 
all that is required for that porpofe, Thb may be done before the tiunpr opens 
^xtemaUy, or even after the excrefoeiice |ias begun to flioot out, and will be 
l>ettcr cffi^Aed by difledion than efcharotics, fince the fucceis of the operation 
.d^nds ^pon the whole 4>f the bag being removed. 



5 






Vol. LXXXI. P 



[ ^o6 ] 



yil. Confiderattons on the Convenience of meafuring an Arch of 
the Meridian^ and of the Parallel of Longitude^ having the 
Obfervatory of Geneva for their common InterJeSiion. By 
Mark Auguftus Piaet, Projffor of Phihfopby in the Aca^ 
demy of Geneva ; in a Letter to Sir Joieph Banks, Bart. 
P. R. S. 



Read February 24, 1J9U 



S I R, 



THE accurate knowledge of the dimenfions and true figure 
of the earth is not a matter of mere curiofity* Aftro- 
nomy and navigation are fo clofely connedled with it, that the 
philofophers of the prefent century have purfued this enquiry 
through the moft difcouraging difficulties; and governments 
themfelves have contributed coniiderable fums towards its 
fuccefs. 

We know that, potwithflanding thefe efforts, the end is not 
yet obtained. There arc five different conclufions on tliis fub- 
jeft; one of which is given by SirJsaac Newton's theory ; 
the others are the refult of four different meafurements, which 
appear the moft creditable among thofe that have been per« 
formed. The extremes give t-J.^ and ^4.^ for the difference 
between the polar and equatorial diameters of the earth, that 
is, two fractions, one of which is more than double the other. 
The caufe of thefe difagreements is yet unknown ; perhaps 
the figure of the earth is really irregular ; perhaps the feveral 

' nieafure* 



Mr. Pictet's ConfiderationSj &c. 107 

meafurements have not been executed with the very minute 
exaftnefs requiiite in {o nice and fo important an undertaking. 

The liberal and well condu£ted operations carried on by the 
Royal Society, under the direftion of the late General Roy, 
for the trigonometrical determination of the diflance between 
the Obfervatories of Greenwich and Paris, render this laft 
fuppofition extremely probable. It now feems evident, that 
the fubftances employed before for the aftual meafurement of 
the bafes muft have been influenced in their length by pyro- 
metrical and hygrometrical efFedts, which were either unknown 
or ill-eflimated at that time. The inftruments alfo for obferv- 
ing the celeftial and terreftrial angles were far from the per- 
fedion to which they have fmce been brought. In a word, the 
whole of the woik (hould be again undertaken with the far 
greater degree of accuracy which is now within our reach. 

Struck with the importance of thefe fa£ks, I take the liberty 
of tranfmitting to you, Sir, for the confideration of the Royal 
Society, the piefent plan for meafuring, by a commiffioti of its 
IVIembers, an arch of the meridian, and of a parallel of longitude, 
having the Obfervatory of Geneva for their common point of 
interfedlion. Frequent excurfions in our neighbouring moun- 
tains have convinced me, not only that the meafurement could 
be made, but that it would be perhaps the mod eafily executed 
of any hitherto attempted. The rough (ketch, with its expla* 
nation, joined to the prefent Paper, will give fome account of 
the particulars which I have been able to colled): relative thereto. 
At prefent 1 (hall only lay before the Society a general furvey 
of the undertaking. 

The beft maps place the town of St. yean de Maurienne nearly 
fouth of Geneva, at the diftance of about 58 minutes of lati* 
tude. It would be impoilible to extend the meafurement 

P a fancier 



ic8 Mr. Pictet's Confid^rttttMs pn the 

farther fouthwardsythe central and inaccedible chain of the Alpr 
being in the waj ; but if a greater arch Aiould be defired, it 
might be eafily protraded about 26 minutes north of Geneva. 

I lately made an excurfion to St. Jean de Maurienne, to exa- 
mine whether the poiition of the town would be convenient ia 
other refpedts ; and if, in particular, the lateral attradion of 
fome neighbouring mountain was not to be feared. It appeared 
to me^ that the place being furrounded by mountains of pearly 
equal maifes, and (ituated at almofl equal didances, their 
efie^s would be hardly perceptible \ and, fuppofing there ihould 
remain any doubt about their influence, this influence might 
be eafiiy afcertained' by zenith diftances, obferved at the twa 
extremities of a little plain in which the town is built, and 
compared with the real diftance of the ftations, determined by 
an adhial meafurement. That town being the refldence of 
a bifliop, and containing near 3000 inhabitants, might furniih 
the obfervers with a convenient building for the zenith itGtor^ 
and the^occafional help and neceffaries which might be required^ 
The great poft-road from hence into Italy, over Mount Cenis^ 
palling through it, is al(b an advantageous circumftance. 

The difpofltion and bearing of the vallies from that town^ 
which would be the fouthermnoft extremity of the arch, is 
advantageous ibr the feries of triangles : for I have feen 
from the top of a mountain near St. Jean, called Le Mont 
Sapeyj two parallel chains extending to the north on both fides 
of the river Arc^ and there appeared to be in their iummits a 
great choice for convenient ftations, as far as the <:onfluence of 
the Arc and the river IfSre near Aiguebelk^ from whence the 
mountains in the parallel of Chamberi are all viiible. From 
this laft parallel to Geneva, and farther, there are not only no 
difficulties^ but the fiatioiULaseibr the greateft part a^eady deter- 
mined. 



Cottvemence of a Mcafurement near Geneva. izg 

mined. The mountains and lines drawn in black, on the map fiib- 
joined (Tabjl.), (hew the ftations and triangles already obferved ; 
thofe in red * are only prelumed, but their places will probably 
ditFer little m reality from tiiofe which are there indicated. The 
map, as to the iituation of mountains, has no pretenfions but 
to fuch an exaftnefs as may refult from angles obferved with a 
Hadley's fextant, without a redudion to the horizon ; but 
the fituation and figure of our lake is exadly true, being the 
refult of a minute and accurate furvey taken by the late Pra- 
feflbr Mallet and myfelf. 

The vifible part of the meridian of Geneva is foon termi* 
nated northwards by the firft chain of Mount Jura; but the 
country opens to the N.N,E. and the northern ftation might he 
eafily chofen in fome place of the Pays de Vaud^ vifible from 
the Obfervatory of Geneva, and which: could be determined 
by only one additional triangle. I take the liberty to point out 
two fuch places. The one, called Vlncy^ about i6 minutes^ 
north of Geneva, and where the circumftance of my poffeffing 
a country houfe would facilitate the difpofitions neceflary for 
the aftronomical obfervations. The other pUce is the top of a 
mountain, called the Dent de Vaulion^ making part of the chain 
of Mount Jura, and where an occafional obfervatory might be 
creeled without much difficulty : it is lo minutes north of 
Vincy, or 26' of Geneva. The whole arch from 5/. Jean de Mau* 
rienne to this laft place would be about i degree 24 minutes. 

The caleftial obfervations might perhaps be made in the four 
places above mentioned ; and the meridian arch would be thus* 
obtained in three portions, whofe comparifon with the ter- 
reflrial fedions, meafured geometrically, would be a proof of 
the accuracy of the operation* 

^ Ift the engraving of this map, dotted linci arc cmj^loycd, to txfitit what- 
cter waa dxawA wiih red in the original. 



110 Mr. PicTET*s Confiderattons on the i 

It is obfervable, on the infpeftion of the map, that the 
chain of triangles lies moftly on the weft fide of the meridian 
line. 1 was forced to difpole it thus, to be within reach of the 
only place where d convenient bafis could be found, vix. the 
niarflies of Chouiagne. I have feen this place, and am well 
aflured, that the meafurement in a convenient feafon would be 
attended with no difficulty. The difpofition and proportion of 
the bafis of about 29,000 feet traced on the map, are therefulc 
of operations I have made on the fpot. 

The fouthern part of the meridian line, vifible from the 
Obfervatory of Geneva, paffes over the fummit of a mountain 
called Mount SalivCy where we have a meridian mark, at the 
diflance of about 5600 toifes, and at the height of about 500 
toifes above the level of the lake. I have obfervcd from that 
fummit, that the fame line protraded fouthwards is not inter- 
cepted by the mountains but at a great diftance, and in a place 
which, as far as I could judge, muft be near the fouthern end 
of the arch. I am ignorant if that place is acceflible ; but if 
it (hould happen to be fo, it would be a fortunate circumftance, 
inafmuch as it would offer a very fimple, quick, and accurate 
verification of the direftion of the meridian line refulting from 
the chain of triangles, by aftually protraSing the vifual line 
given immediately by the tranfit inftrument of the Obferva- 
tory down to the end of the arch, by the help of two inter- 
mediate ftations only. I do not believe that fuch a verification 
has ever yet been praftifed. 

We fee hitherto no local difficulties in the meafurement of 

an arch of abouk 84 minutes of the meridian of Geneva. The 

meafurement of the parallel of longitude, eaftwards of the fame 

place, feems to be of a ftill eafier execution, infomuch that I 

I believe 



Convenience of a Meafurement near Geneva. 1 1 1 

believe there are few places on earth better difpofed for thfi 
operation • 

The Republic of Fallals in Switzerland offers an extenfive, 
broad, and nearly ftraight valley, bordered on both (ides by 
high mountains. It is fituated about the parallel of Geneva, 
runs eaft ward for many leagues from the town of M^r//^«y, and 
to the weftward is feparated from the mountains of Chablats 
in Savoy, by* a very lofty chain, in which there is an acceffibic 
fummit, called T!be Glacier de Biiet^ or La Mortlne. 

This mountain is placed, as by a miracle, in fuch a pofition 
as to be vifiblc from the Obfervatory of Geneva, and about lo 
minutes weft of it, as alfo from almoft every elevated (ituation 
in tbe Haut Vallais. Its fummit is acceilible by a much eaiier 
afcent than that which was difcovered by MelT. de Luc ; and a 
iigaal made there by the Indian lights would be vifible eaft and 
weft along the parallel, to the whole diftance of perhaps two 
degrees between the two extreme ftations ; for as the obferva- ' 
tions relative to the regulating of the clocks do not require any 
confiderable apparatus, they could be performed in ^the moft 
diftant hamlets from which the figual Ihould be vifible. 

As to the trigonometrical meafurement along the parallel, 
one may conclude, from the triangles delineated on the map, 
that it might be executed with a fmaller number of operations 
than that of the meridian arch. I was aftifted in the defigna- 
tion of the probable ftations in the Fallals by my ingenious 
friend Mr. Wild, Direftor of the Salt Works . and Mines of 
the Republic of Bern, and refiding at Bex ; from whence, by 
frequent excurfions, he has acquired a fufficient knowledge of 
the names and pofitions of the neighbouring mountains to 
enable iqe to complete the fketch in the eaftern part of the 
parallel. 

Should 



112 Mr. PicTfiT*s Confiderationi en the 

Should the metnod, propofed by the late General RoY •, 
for afccrtaining the length of the parallel independently of 
aftrouomical obfervations, be adopted, it might be carried into 
execution with no great difficulty from the fummit of the fame 
rfaountain, where we juft now fuppofed the fignal by the In* 
dian lights to be placed. 

The triangles relative to the meafurement of the parallel 
make but one fuite with thofe of the meridian, and there are 
four very convenient places along the fame parallel for mea- 
furing ^iifes of verification^ They arc perfedly level plains, 
forming the bottom of the valley through which the Rhone 
flows between the towns of JiigU and Villeneuve^ and betweeii 
Martigny and Sbu. Their relative iituations are roughly indi« 
cated in the map. The ^bove general coniiderations, together 
with the particulars which are fubjoined to the fketch, feem to 
afcertain the full prafticability of the enterprise. May I be 
allowed to add a few refledions on its conveniency } 

The re-union of the two meafurements (of latitude and loa- 
^itude) in the fame fpot^ is an advantageous circumftaoce ; 
and the m^re fe, if we coniider that this fpot lies between the 
45 and 46th degree, that is, in the mean latitude between the 
pole and equator, near which latitude the mean radius of the 
earth takes placid in the well-founded fuppofition <^ its being a 
Spheroid. This radius, found by the moft acoirate meafure* 
cient hitherto attempted, would become a ftandard, and to 
which the refulcs of the equatorial and northern meafurements 
being conipared, the true £gure of the earth would be the 
better afcertained. 

Thepofition or relative longitude of the meridian of Geneva 
isweil determined by a great number of obferved immerfions 

* Fhil, Tranf. 1787, p. 216. etfeq« 

5 and 



Convenience of a Meafurement near Geneva, i j j 

aiid emerfions of the fatellites of Jupiter, and by Tome 
occultations of ftars by the moon. Thefe obfervations were 
performed by the late Profeffor J. A. Mallet, Mr. J. Trem- 
BLEY, and myfelf. The greater part of them are already cal- 
culated, and their mean refult muft be near the truth. The 
latitude of the fame place would be afcertained by the celefHal 
obfervations eflential to the meafurement, and would verify 
our determination taken from the obferved culmination of ze- 
nith ftars. Laftly, the height of Geneva above the level of 
the Mediterranean Sea (which is fuppofed to be about 196 
toifes) can be obtained with a fufEcient precifion from the baro« 
metrical obfervations which for feveral years paft have been 
regularly made here. 

The Obfervatory of Geneva, in which, (incc the death of 
my late friend Profeilbr Mallet, I have continued a feries 
of obfervations, would be at the free difpofition of the Com- 
miffioners whom thi Royal Society (hould think proper to en- 
truft with the whole work. It is furnilhed with the following 
inftruments, and confequently there would be no occafion for 
fending thofe of the fame fort from England. 

1% A very good trandt inftrument of 5 feet, made by Sisson* 
The telefcope is achromatic, magnifying about 70 times. 

a% A quadrant of 2i feet radius with two achromatic tele* 
fcopes and a micrometer fcrew. The quadrant is moveable on 
an azimuthal circle. The whole made by the fame artift. 

3'', Two aftronomical clocks, with gridiron pendulums. 
One remarkably good, made by the late Shelton ; the other by 
Le Paute. This laft might be carrie4 to any of the ftations. 

4"", An achromatic telefcope of 10 feet, made by Dollond, 
with three magnifying powers 

VoL.LXXXI. Q 5% 



114 ^^^ Pi c T ET*s ConJiJerattons on the 

5*', A 3i feet achromatic, with great aperture, and four 
magnifying powers, made alfo by Dollond, mounted on a pa- 
rallaftic ftand, and carrying occafionally an ocular micrometer*^ 
6% A very good Ramsden's 30-inches achromatic refraSor 
with four powers ; befides fomc other telefcopes and inftru- 
ments of lefs importance. 

The capital inftruments which, I fuppofe, it would be ne- 
ceffary to fend frpm England, would be one or two zenith 
fedlors, one or two clocks, and the inftrument for obferving 
the terreftrial angles, the accuracy of which is of the utmoft im- 
portance. I faw in London, three years ago, that made by 
Mr. Ramsden, and employed fo fuccefsfully in the late mea- 
furements from Hounflow Heath to the French Coaft. It is a 
matter of doubt to me, whether this precious inftrument would 
be allowed to go out of the kingdom ; and even ihould that be 
peraiitted, as far as I can judge from the impreffion it has left 
on my memory, it would be too heavy tmd of too large a bulk 
to be conveniently carried to the top of mountains. The in- 
ftrument ought perhaps to be made of feparable parts eafily 
put together, and capable of being fteadily adjufted : they 
might be packed feparately in a box, not exceeding the common, 
charge of a man. The boxes could be fo contrived as to fill a 
larger one, fufpended on fprings in a fmall narrow carriage 
made on purpofe, and in which &11 the neceffary things befides 
could be coUefted. Such a difpofition would be very conve- 
nient, not only for fending the inftruments fafe from Eng- 
land, but alfo to carry them from one ftation to another 
through crofs country roads, with more quicknefs and Icfs 

^ We are indebted for the poflcffion of that valuable inftrument to the n)u!iifi<» 
cence of my learned friend M. de Sauisure^ who gave it to M. Tbevblsy^ 
to whom it now belongs. 

Z trouble 



Convenience tf a, Meafurement near Geneva. 1 1 5 

trouble and danger. A convenient tent, to (helter the inftru- 
ments in the ftationsi (hould be added, or might be made at 
Geneva. 

The glafs rods for the meafurement of the bafis could be 
drawn of any convenient (hape, in a glafs-houfe not far diftant 
from Geneva. The thermometers, and any additions or repairs 
the apparatus might require, would be duly performed by MefT- 
Paul, eminent artifts of this town i and we abound with 
artifts of inferior merit. 

Thus far, Sir, I forefee no capital obflacles to the execution 
of the plan I have the honour of laying before the Royal So- 
ciety. AH the data feem in favour of it ; and I may add, as 
another favourable circumftance, that the ftar Capella of the 
firfl magnitude culminates between the zeniths of Geneva and 
St. Jean Maurienne^ and confequently might be obferved fimul- 
taneoufly from both ftations at any -hour in which the feafon of 
the year would bring its meridian traniit. 

I (hall conclude this Paper with a few more reflexions on 
the undertaking in general. 

SuppoHng it to be the intention of the Royal Society to 
attempt the inveftigation of the true figure of the earth, by 
meafurements executed in different parts of the globe ; this 
firft operation, performed in a foreign country, might be looked 
upon as a kind of pre>jiou» trial for the obfervers, a fort of 
initiation, in which fon^e difficulties, owing to the nature of 
the foil, but no true hard(hips> would be encountered* The 
whole of the work, except perhaps one fingle ftation, would 
be carried on in the Kmg of Sardinia's dominions, and in fome of 
the Republics of Switzerland ; countries, where no moral nor 
political obftacles would be ftarted, and where the inhabitants, 
far from being troublefomc, would afford every afliftance and 

Q 2 comfort 



1 16 Mr. Pictet's Conjideratlons tm the 

comfort in their power. I may add, that none of the moun* 
tains on which I have obferved, and which are pointed out la 
the map as likely ftations, prefent any danger. 

If a furvey of that kind, executed in a mountainous coun- 
try, is liable to fome difficulties, it offers, on the other hand, 
advantages which perhaps more than overbalance thofe diffi- 
culties. 

Firft, the vifual rays being lefs interrupted, the triangles 
become larger, and the ftations fewer in number ; whence the 
labour of the obfervers, and the chances of error, are by fa 
much dimiuifhed. } 

Secondly, Thefe fame vifual rays proceeding through ftrata 
of air Icfs denfe and more free from the vapours which com- 
monly thicken the lower parts of the atmofphere, the danger 
of irregular refra£tions is by fo much lefs, and the fignals may 
be more diftlnAly perceived from great diflances. 

Befides thofe advantages which chiefly concern the meafure- 
ment itfelf, the country would offer facilities for other natural 
enquiries, not unworthy the attention of philofophical men, 
and which might eafily be united with the capital objeft of 
thefe labours, with which obje£l fome of thefe enquiries are 
intimately united. I range among them. 

The accurate determination of the length of the fimple pen- 
dulum, which beats feconds in this mean latitude. 

Experiments to be made on the ofcillations at different 
heights, with an invariable pendulum. 

Experiments on the lateral attraftion of mountains repeated 
and varied. 

Obfcrvatiqns on meteors, and feverat atmofpherical phaeno- 
mena relative to refradions, to heat, to hygrometry, to cleftri- 
ci^, &c* 

But, 



Convenience of a Meafwrement near Geneva. 1 1 y 

But, above alU the improvement of barometrical nieafure- 
ments would moftly deferve the attention of the Commiflioners. 
Nothing, as it fcems, is now wanting in the theory of the 
operation ; and it is only from a number of actual obfervations, 
made at different heights, and with every due precaution, 
compared with geometrical meafurement, that the co-efiicient 
(either conftant or variable) to be applied as a correAion for the 
atmofpherical heat, will be obtained That reiearch muft be 
merely empirical ; the effe£); fought for being the refult of 
many complicated caufes, fome of which are yet unknown* 
The real height of every ftation being well determined, tht 
time to be fpent there for other purpofes would allow a num- 
ber of barometrical obfervations in varied tircumflances $ and 
from thefe obfervations, rightly compared between themfelves, 
interefting and ufeful refults may juflly be expeded. 

I have the honour to be, &c. 

MARK AUGUSTE PICTET. 

Geneva, Oft. 30, 1790, 



Eclahr^Je 



;i 1 8 Mr. PiCTET^s Conpderatiom on tbe 



Eclmr€ijcm$nsfur la Carti^ qui accompagne h Profit di Mifure 
prifenti i la Societi Royak^ par M, A. Pi£kct 

(See Tab. IL) 

DANS refquifle de la fuite de triangles k laquelle le prefent 
developpement fe rapporte, les montagnes ou les lignes tracees 
^n rouge reprefentent des pofitions tir6es des cartes, ou d'une 
iufpeftion generale dc*la direftion des montagnes et des vallees*. 
Ce qui eft defline en noir indique les pofitions d6terminees par 
*des angles et des mefures reellement prifes ; mais fans pretendre 
cependant d plus de precifion que la nature de la chofe ne Texi- 
gcoit. Enfin ce qui eft trac^ leg^rement en couleur noire montre 
feulement qu'il exifte des montagnes \i o^ ellej font ainfi 
indiquees. 

Les deux Hgnes rouges qui fe coupent ^ angles droits dans la 
carte reprefentent le merldien et le parall^le de FObfervatoire 
de Geneve dans Tetendue de la mefure propofee ; c'eft-i-dire 
environ i^ z^- pour le meridien, et environ 2°, pour le paral- 
•lele de longitude. 

Le feul endroit dans lequel j'aye pd trouver un emplacement 
<:onvenable pour une bafe relative k la mefure dc Tare du merl- 
dien, eft fitue a Toueft de cet arc, et a-peu-pres vis-a-vis du 
milieu de fa longueur ; ce font les marais de Choutagne. lis 
ofFrent une plaine qui s'etend do nord au fud dans une efpace 
<l*cnviron 2 lieues ; elle eft bornee ^ Toueft par le Rh6ne, et a 
i eft |>ar une montagne tres voifine nommee la montagne de 

* See NotCi psige 109. 

Chou* 



Convenience of a Mtafurement near Geneva. up 

Cboutagne, qui fe prolonge au nord et au fbd beaucoup plus 
loin que la plaine elle meme. Le fol de cette plaine eft (i par* 
faitetnent horizontal qu'il paroit n^offrir d*autre elevation que 
celle qui refulte de la courburc dela tcrre et d'une route qu*6u a 
pratiquee au travers de cette meme plaiue de Teft a Toueft. 

La Hgne ^ 3 repr6fciite une b&fe d'cnviron 25000 pieds An- 
glois de longueur, tracec dans cdtte plaine, et la ligne b^ une 
autre bafe prife dans la mSme plaine, et dont je parlerai tout a 
rheure. Le fol du marais eft ferme le long de ces deux lignes, 
et en sVidant de quelques ponts dans les endroits ou ils feroient 
ii6ceflaires, la mefure tie fouffriroit aucune difficult^^ Ulie 
grahde partie de la plaine eft en prairie pendant Xhxi ; il n*y a 
que tr^s peu d'eau datis le refte ; je Tai trouve encore tres prati- 
cable au milieu d'Oftobre dernier, terns oil j*y ai fait les ope- 
rations r^latlvef d la pr^fente efquifle. 

Les deux extremit^s ^ et ^ de la bafe font marquees par deux 
b&timens qui feroient utiles dans le voifinage des deux ftations : 
Tun eft une petite ferme au point j, nommee Che% Thevenet^ 
et l*autre tine Briquetcric k Textremite b. Ges deux points 
font vifibles Tun de Tautrc, et je remarque en paflant que les 
inftrumens pourroient ariiver par eau depuis TAngleterfe 
jufques i la ftation b^ par la voye de Marfeille et du Rh6ne. 

J*ajouterai que tout le c6t£ oriental de la bafe, le long du pied 
de la montagne, eft tres peuple ; c*eft un vignoble confid^rable, 
et Ton auroit tout-a-fait i^port6e le logement et tons lesfecours 
nkeffaires au travail de la mefure ; et quoique la plaine foit 
Ebar6cageufe, le vignoble que la borde paffe pour tres fain. 

II n*etoit pas facile de trouver fur le foramet de la nKjntagne 
ChoUtagne deux ftations qui reuniflent les conditions necef- 
faires; Ikvoir i"^,D etre vifibles des deuxextremitesde la bafe qui . 

font 



120 Mn Pictbt's Cm/Uerations on the 

font abaiflees de 8 d lo degres fous rhorifou. 2^*, D'etre 
vifibles Tuue de Tautre. 3^*°, D'etre placees de maniere qu*ou 
put decouvrlr les fommices a Teft du cote oppofe d la bafe. 4^ 
enfin. D'etre aflez diflantes entre elles pour fournir un cote con- 
venablc au premier triangle de la chaiae. Les points marques 
c ctd font les feuls, a ce que je crois^ qui reuniffent ces condi- 
tions. J'ai m^me quelque doute que la montagne de la 
Caille foic viable du point c fans elever rinftruiinent de quel- 
ques pieds. On voit que la diftance c 1/ de ces deux points eft 
un peu moindre que la longueur de la bafe^ et Ton trouvera fans 
doute que Tangle que cette ligne fouftend fur la montagne de 
la Caille eft trop petit ; il n'cft efFe£livemcnt que de 1 7 degr6s, 
et ibus cette obliquite et d cette diftanoe une erreur de ^'^ en c 
ou en d allongeroit le c6te oppofe de pieds. Cette 

confideration pourroit etre jugee fufiifante pour engager les 
cx^mmiffaires d preferer a la fiation c une ftation e que j'indique 
fur le fommet feptentrional du mont Colombier, quoique ce 
point foit iitue fur le territoire Francois. La bafe eft placee 
tres coavenablement pour determiner ce point, et (i Ton aban- 
donnoit ainfi la ftation c^ cette meme bafe pourroit etre pro- 
loDgee du cdte du nord d'environ 3 a 4000 pieds; en rap- 
prochant un peu vers Teft fon extremite feptentrionalcf en lui 
donnant la diredion 3 jS ; elle feroit alors encore plus fevorable- 
ment difpofee pour determiner la ftation e^ d'oii, jufques d la 
ftation d^ tres bien determinee par la mSme, bafe fur la mon- 
tagne de Choutagne, la diftance feroit d*environ 7500 toifes, et 
Tangle oppofe en /fur la montagne de la Caille d'environ 34 
degresy c*eft-d-dirc double du precedent. Cette difpofition du 
premier triangle de la chatnc feroit fans contrcdit plus avanta* 
geufe que la prec^dente. 

3 Lc 



Convemcnce (fa MMpn^mtnt ne^r Geneva. i^^ 

,.Le fXK)Qt Colombier eft eleve d^eaviron 650 toiias * au- 
deflus du niveau de la plaine ; les pc»nt$ c ct d fur la xnontagne 
de Choutagnc font ^lev6s d'eaviron 380 toiCes, ct la motitagne 
de la Caille d'eavirou^ zoo toifed feulemeiit ; c^efl: la plus bafle 
de toutes celles qui fervent a des flatixms ; mais comme die 
eft tout-a-faie ifolee, elle eft vldtiile de tous los cdt^s a une di(^ 
tance fufiifante. 

Depuis les points f tt d on d^termiiie la ftation g fur la 
Tournette; et ccs trois pduts forment le trbngle central d'ou 
Ton proc^de ^nfuite au nord et au fud dans ladtredbn de la m6ri- 
dicnnev La Tournette eft une montagne elevfe d^enviroii 
xooo toifes au-delTus du Lac de Geneve ; elle eft ifblee, et oftre 
un des points de v{le les plusfrappans et les plus etendus qu'on 
puifle trouver dans ces regions. On apperfoit trds bien depuis 
ce fommet non feulement les deux extremities de Fare du m6ri« 
dien» mais encore prefque toutes les ftations, excepte celles 
qui font dans le Vallais au-dela du glacier 4e Buet ou de la 
Mortine. Le fommet de la montagne d*ou j*ai obierve mes 
angles n*eft pas du plus facHe acc^s ; mais j'4i remarque i envi« 
ton 1 50 toifes plus bas un endroit tresacceffible, nomme le Plan 
du Rivray, qui fcroit convenable pour la ftation. L'infpeSion 
de la carte montre combien cette ftation eft importance, puif«> 
qu'elle n*offre pas moins de fept points A obferver. 

En partant du triangle central dfg pour aller ^m midi, on 
d6terniine par les ftations dttgX^ ftation h fur la Dent de Ni« 
volet. Cette montagne eft tres vcnfine de Chamberjr, capitale 

* Les hauteurs de la plupart des ftations he font indiquees qu'sl-peu-prcs, ct 
pour donner une idee des diredHons refpe^ives des rayons vifuels relatiirement i 
rhorifon, et de la necefBte d*avoir un inftrument dont le oiouvcmeac dans les plant 
verttcaiix foit de la plus extreme precifion. 

V0L.LXXXI. R de 



122 Mr. PiCTET^s Confideratiom on tie 

de la Savoye ; et quoique fort efcarpee k Toueft, elle eft, mV 

t-on dit, d*un facile acc^s du c6te dc Teft. 

II exifte vers le bord occidental du Lac du Bourget une 
montagne appellee la Dent du Chat, fur laquelle je fuis monte^ 
et dont j*ai determine la pofition au moyen d*une bafe qui eft 
defignee fur la carte. Cette montagne eft 61ev^e d'environ 650 
toifes au-deflus du Lac du Bourget^ et acc^flible, quoiqu^avec 
quelque difficult6 ; elle ofFriroit une ftation fubfididre, dans le 
cas ou celle fur la Dent de Nivolet feroit impraticable, ce qui 
n'eft cependant nullement probable. La pofition de cette der- 
niere feroit d^ailleurs infiniment meilleure rilativement i la fuxte 
de la chalne. 

Avec les ftations ^ et A on determine le point / fur une mon* 
tagne que j*ai vde depuis la Toumette, qui m'a paru tres ac- 
ceffible, et qui termine la chaine qui accompagne la rive droite 
de la riviere d'Arc depuis St. Jean de Mauriennc. Jignore Ic 
nom de cette montagne ; et c^eft ici que commence la partie de 
ma carte qui n'offre que des probabilites. 

Des ftations h et 1 on determine le point ij oil les cartes indi- 
' quent une montagne quViles nomment Coceirop. Cette mon« 
tagne, formant Textremite d*une chatne cntre deux valines dans 
la diredlion des deux ftations / et h, dolt etre vifible d6puis 
l^une et Tautre. C*eft aux environs de cet endroit que j'ai Keu 
de prefumer que la meridienne de TObfervatoire de Geneve, 
prolong6e au fud depuis le fommet de la montagne de Sal^ve, 
vient pafler, fans etre intercept^e dans Tintervalle par aucune 
des montagnes qui s^y rencontrent. 

Avec les ftations / et k on determine la ftation /fur la chaiae 
qui fepare la Mauriennc de la Tarentaife, et dans laquelle j'ai 
vA plufieurs fommit^s acceflibks : et enfin avec les ftations 

i et 



Convenienee of a Miajkntmnt Mar Geneva. i %^ 

I et /on determine la ftation m fur le mont Sapey, ou j'ai ^te, 
tX d'ou j'ai vu la dircdlion geaerale des chatnes telle qu'elle eft 
indiqu^e fur la carte ; et en particulier que le rayon vifuel m k 
efl: parfaitement libre. Du mont Sapey tt du point /, choifi 
convenablementy on determine finalement St. Jean de Mau- 
ri^ne. 

J'ai obferve en montant le Sapey nne tres haute montagne 
inacceflible, fituee au midi de St. Jean de Maurienne^ et dont le 
fommet offre trois aiguilles contigues de la forme que j*ai def- 
fin^fur la carte, et qui m'ont paru faciles a reconnoitre de loin. 
Ces aiguilles, que j*ai tres bien retrouvees enfuite depuis la 
Tournette, fe nomment, a ce qu*on m'a dit, les Aiguilles 
d*Arve ; et cllcs m'ont fervi a i^eterminer a-peu-prSs la poiition 
de la ville de St. Jean relativemeut a la meridiennede Geneve; 
du moins d m^aifurer qu*elle ne s'ecarte pas beaucoup de cette 
meridienne. Je ne repeterai pas ici ce que j*ai dit daps le Mo- 
moire fur la convenance que je vois i la choifirpour terme meri- 
dional de Tare A mefurer^ 

Je rcprends le triaugle central dfg pour marcher de-U vers 
le nord de la chaine des triangles. 

Les ftationsy et g determinent la ftation o fur le Pithon de 
Salive. Ceft un rocher ifbl^ et du plus facile acces, qui do« 
mine la montagne; il eft elev6 d*environ 512 toifes au-defTus 
du Lac de Geneve^ et parf^tement vifible depuis TOblervatoire 
de cette ville. 

Avec les ftations^ et on ohtknt la ftation ^ fur le M6Ie. 
Cette montagne eft elevee d'environ 750 toifes au-deffus du Lac 
de Geneve ; elle eft de forme conique, parfaitement ifolee, d'un 
fiacile acces, et ofTre une des plus belles ftations de toute la me- 
fure ; elle prefente d^utres avantages pour des experiences fur 

R 2 Tattrac- 



1 24 Mr. PicTET*s Confiderattom on tht 

Tattraflion laterale^ pour des obfervations barometriques et 
m^teorolpgiques ; en un mot, eile merite toute Tattention 
des obfervateurs, auxquels elle oflFrira d*ailleurs une ftatlon auffi 
importantc que celle de ta Tournette. 

Avec les ftations tt p fur le Pithon et fur le Mdle, on ar-* 
rive d rObfervatoire de Geneve, fur lequel j'ai donne dans le 
M^moire des details qui me paroiifent fuffifans; je le dcfigne 
par la lettre y. 

Avec les ftations ^ et y on determine un point quelconque r, 
acceffible et habitable dans la chatne du Mont Jura, aux envi-* 
rons du parallele de TObfervatoire de Geneve, et qui forme Ic 
terme occidental de la mefure ; on a d cet egard beaucoup de 
choix ; le glacier de Buct, fur lequel fe fera le fignal, eft vifible 
de tous les points du Jura pres du parallele de Geneve. On 
trouve des habitations jufques vers le fommet de cette derniere 
montagne, et on choifira la plus convenable pour y ^tablir 
Tobfervateur et fa pendule. 

La ligne qp^ menee de TObfervatoire au M61e, fert de bafeau 
triangle qps^ dont le fommet x eft i Vincy, village du Pays de 
Vaud, vifible de TObfervatoire de Geneve, et dans lequel j*ai 
une maifon de campagne, que j*ai ofFerte dans mon M^moire 
pour y faire les obfervations aftronomiques dans le cas ou I'oti 
jugeroit ^-propos d*etendre jufques Ik Tare du meridien. Cet 
endroit eft eleve d'environ 80 toifes au-deftus du Lac, et feroit 
commode pour les obfervatcurs. 

Ce triangle qps qui appartient a la meridtenne, eft auffi le 
premier de la fuite deftinee a determiner la longueur du paral* 
lele a left. La ligne ^j, menee du M61e a Vincy, et les ftations 
p et T, detcrminent Tune ou Tautre des Montagues du Chablais 
appell6es la Dent d^Oche et la Cornette. Elles font voifines 

Tune 



Cofruenience of a Meafunmtnt near Geneva* 125 

Tune de Taatre, et je les d^figne toutes deux, parce que la Dent 
d*Ochc fur laquelle je fuis moute eft d'un ai!ez difficile 
accis ; la Cornette fur laquelle je n'ai point 6te eft, dit-on, 
tres facile k monter, et a de plus Tavantage d*etre un peu plus 
haute que la Dent d'Oche (qui eft cependant elev6e de 940 
toifes au deiTus du lac), et un peu plus a Tcft du c6te des mon- 
tagnes du Vallais. Je pref^rerois done la ftation de la Cornette 
telle que je I'ai indiqu6e. 

La ligne tp de la Cornette au Mdie fert de bafe au triangle 
ftVy dont le fommet eft a la Dent de Vaulion, montagne dans 
la chatne de Jura, jufqu^ou je propofe d'etendre encore,, fi Ton 
vcut. Tare du m^ridien. 

Cette meme ligne tp fert de bafe i un triangle piu^ dont le 
ibmmet u eft au glacier de Buet, qui (era ^ la fois une ftation 
pour mefurer des angles, et le lieu du Hgnal pour les obferva- 
tions relatives k la mefure aftronomique de Tare du parall^le. 
Cette montagne, elevee d*environ 1300 toifes au-deflus du Lac 
de Geneve, eft couverte d'une couche de neige permanente ; 
mais cela n'empecheroit pas qu'on ne p{it y faire commode- 
ment les oblervations dans les mois d*Ao{kt ou de Septembre. 
On peujt batir une petite cabane pour le fSjour neceflaire, fur 
des rochers d*ardoife qui font voifins de la fommite. La mon- 
tagne n'eft pas d*un acc^s difficile par la route que M. Excha- 
Qj/ET a le premier iiidiqu^e, et que j*ai fuivie a mon dernier 
voyage a cette montagne ; et lors mdme qu*il refteroit quelques 
difficultes a vaincre, cette ftation eft fi belle et fi importante, 
qu'on ne manquerok pas de motifs et de courage pour les 
furmonter. 

On remarquera qu*il fe formo ainfi autour du M61e un 

exagone irregulier, ce qui fournit Foccafion d'une verifica- 

2 tion ; 



i iJI Mr. ^icTBt'g Confidsratkm w thi . 

tion; et quWre autres, la ligne pu peut dtre dgterminee dd . 
deux manteres ; favoir^ immediatetneut par le triangle pgti^ 
et en faifaint le circuit que nous venons de faire par les ftatioos 
goqst. ' . 

Ici commence la partie de ma carte que je dois k la Cotnplair 
fance de mon ami M. Wild. II me previent que les pofi» 
tions qu il m*a deHgnees ne font pas exaftes ; mais il ne s*agif- 
foit que d'etablir la diredtioa generale du haut et bas Vallaitt 
de marquer les principales montagnes acce(Iibles» eC les ea* 
droits ou Ton pourroit mefurer des bafes de verification* La 
carte du Vallais qu*tl m*a envoyee, et dont la mienoe offre 
Textrait^ m*a paru atteindre ce ouU II ed evident que le tri* 
angle qui a pour bafe la diftance de la Dent de Morcle$i la 
Catogne, et qui fe termine au Rothomt non loin de la fouroe 
du Rhone, auroit Tangle dtt fommet beaucoup trop aigu ; 
mais il n^eft pas douteux aufli que dans une valUe large et 
prefque droite, comme Teft celle du haut Vallais, on peut 
former facilemetit une fuite de triangles par des flations alter«> 
natives fur les fommets acceffibles des deux c6tes de la vaU 
lee, et arriver i, Textremit^ par tan petit nogibre de ceS 
triangles. 

Les lignes drottes, tracees en rouge dans cette partie de la 
carte, defignent les bales praticables ; ces bafes font au nombre 
de quatre, mais aucune d*elles n egale en longueur celle qu^ 
j*ai trouvee dans les plaines de Choutagne. 

Si le projet dont je viens de developper Tefquifle, eft agree 
par la Societ6 Royale, mon premier foin, des que la faiibn 
le permettra, fera de parcourir le haut Vallais pour decouvrir 
le demier fommet acceflible du cote de Teft, d*ou la Mortiue 
t)u le glacier de Buet foit vifible. Ce point une fois trouve, 
3 j*etablirai 



Uion 



IhiI0t.Tran4.V0l. LXXXI. Tab. H.p.ttS. 




Convenience of a Meafurement near Geneva. 127 

j'etablirai la fuite de triangles pour j parvenir; et Tinoertitude 
qui me refte fur Tetendue totale de Tare du parall^le dont lea 
deux extr^mites font viiiblea depuis la montagnc dont je viena 
de parler^ fera levee. 




METEOROLOGICAL JOURNAL 



KEPT AT THE APARTMENTS Of THE 



ROYAL SOCIETY, 



BT OtDBl or THE 



TRESIDBNT AKto COUNCIL. 



titmm0am 



[ » ] 



METEOROLOGICAL JOURNAL. 






for January- 


1790. 




Time. 


Therm. 


Therm. Baroro. 


Rain. 


Windi. 




1790 




without 


within. 






. ^Vcathtr. ^. 






• 










H. M. 


• 


'• 


Indies. 


Inch, 


Points. 


Str, 




Jan. I 


8 


34 


53 


29,92 




W 


Fine, 




a 


40 


50'5 


30,08 




W 




Fair. 


2 


8 


36 


53.5 


30.37 




ENE 




Cloudy. 




2 


4« 


,,55 


30»S» 




-^byE 




QioxdT. 


3 


8 


44 


53 


30',oi 


0,093 


"WSW 




Cloudy. 


4 


a 
8 


50 
4a 


55.5 
53>5 


30,00 
30.25 




WNW 




Cloudy. 
^oggy. 




2 


45 


55 


30,26 




NW 




Cloudy. 


5 


8 


43 


53 


30,26 








Foggy. 


.' 


«• 


45 


5^ 


%o,a4 


' 


ENE-. 




Clou^. 


6 


a 


'*'40,5 


5»,5 


50,20 




E 




Clowfy. 




a 


40,5 


53.5 


30,22 




SSE 




Cloudy. 


7 


8 


40 


5«,5 


30,42 




WNW 




Cloudy. 




2 


4if5 


54 


30,47 




WNW 




Hazy. 


8 


8 


33*5 


51 


30,44 




WNW 




Foggy- 




a 


35 


S3 


30,40 




WNW 




Cloudy. 


9 


8 


3* 


50 . 


.3«»3« 


. 


» *. 




Foggy. 




2 


39 


53 


30.25 




SSE 




Fine. 


10 


8 


33.5 


50 


30,24 




SW 




Foggy, 




2 


40 


53 


30,22 




W 




Cloudy. 


II 


8 


44 


50.5 


30.13 




WSW 




Cloudy. 




2° 


47 


53»& 


3**'o? 




w^w . 




Clojidy.. ^ f 


12 


8 


49.5 


5l,f 


29,88 


0,025 


WSW 


•a 


Cloudy. ' 




2 


52.5 


56,5 


29,86 




WSW 


2 


Clouc^. 


»3 


8 


50.5 


54 


29,88 




WSW 


2 


Cloudy. 




2 


48.5 


55 


29,86 




WSW 


2 


Raia. 


14 


8 


46 


11 


29,88 


0,073 


NW 


I 


Cloudy. 




2 


47 


29.9Q 




NNE 


I 


Cloudy. 


»S 


8 


4».S 


II 


29,94 


0,030 


N 


I 


Cloudy. 




2 


40 


29,99 




WbyN 


I 


Cloudy. 


16 


8 


40 


53 


30,01 


o,»37 


WNW 


2 


Cloudy. 




2 


46 


-55, 


30," 




WNW 


2 


Cloudy. 



MS T B- 



[ '3 ] 



KCETEOKOLOOICAL jOtTRNAL 

for January 1790. 







Time. 


Therm 


. 'Therm, 


l^rom* 


Ram. 


Winds. 








1790 




withoui 


: witliin. 




■ ■■ML 




Weather. 





























• 


Inehei. 


Inch. 


Points. 


Str. 








[an. 17 


8 


3»»S 


5i 


30.39 




NW 


I 


Cloudy. 








2 


44 


S5 


30.39 




^fN£ 


I 


Cloudy. 






,18 


8 


3« 


Si 


30,22 




ENE 


2 


Cloudy^v 








2 


46 


53.5 


30,12 




£N£ 


2 


Fine. 


, 




*9 


8 


33 


50 


30.14 




£ 


2 


Cloudy. 








2 


38 


sa.5 


30,16 




£ 


2 


Fine. 






SO 


8 


3« 


49.5 


30.25 




E 


2 


Fine. 








2 


35 


5«.5 


29,3^ 




£ 


2 


Fine. 






21 


8 


3« 


SO 


30.44 




E 


I 


Fiir. 








2 


39 


$3 


30,41 




E 


I 


Fine. 






22 


8 


11 


S^*5 


30,38 




E 


t 


Foggy. 








2 


52.5 


30,37 




WNW 


t 


Cloudy. 


* 




*3 


8 


44 


5* 


30.28 




WNW 


t 


Cloui^. 








2 


47 


54 


30,28 ] 


WNW 


t 


Cloudy. 






24 


8 


43 


52 


30,26 




WNW 


1 


Cloudy. 








2 


47 


54,5 


30.17 




WNW- 


I 


Clou^. 






25 


8 


4» 


S*.5 


30,1 1 


0,250 


NNE 


i 


Eaiu. * 








2 


43.5 


55 


30,20 


• 


N 


t 


Pair. 






26 


8 


35.5 


5o»5 


30,22 




WNW 


t 


Cloudy. 








2 


4« 


5a,5 


^,»» 




W 


I 


^air. 






27 


8 


39.5 


5«.5 


29,35 


o,t8i 


WNW 


% 


Fain 








2 


4« 


55 


29,35 




WNW 


2 


Fair. 






28 


8 


II 


52 


2956 




W 


I 


Cloudy. 


^ 






2 


54»5 


29,27 




SW 


2 


Clottc^. 






2^ 


8 


37 


52.5 


29,28 


0,160 


WNW 


t 


Pine. 








2 


^i'S 


54.5 


49,28 




WNW 


'2 


Pine. 






30 


8 


38 


52.5 


29.5 < 




NW 


1 


Cloildy. 








2 


42.5 


54<5 


29,69 




NW 


I 


Fine. 


• 




3* 


8 


38.5 


52»5 


29,62 


OtOI^ 


WNW 


X 


Clpudy. 








2 




-ii:L 


J3£i 




WNW 


I 


Fine. 


^^^ 



a a 



M B TX- 



t ♦ 1 





METEOROLOGICAL JOURNAL 




for February 1 790, 


iTime. iTherm. 


Therm. 


IBaroin. 


Rain. 


Winds. 




»790, 






without 


within. 








Weather. 


H 


M. 








Inches. 


Inch. 


Points. 


Str. 


Feb. I 


T 





37 


52 


29,88 




WNW 




Fine.. 




2 





« 


56 


30,02 




NW 




Fine. 


2 


8 





. 37 


52 


30,20 




WNW 




Fair. 




a 





4S.5 


54 


30.24 




W 




Fair. 


3 


8 





43 


5«.5 


30,38 




W 




CloudjT* 




2 





47 


55 


30.43 




w 




Cloudy. 


4 


8 





4.4 


53 


30,61 




w 




Cloudy* 




2 





46 


54 


30,62 




w 




Cloudy, 


5 


8 





43^S 


5^ 


30,6t 




w 




Cloudy* 




2 





46,5 


54,5 


30,58 




w 




Cloudy. 


6 


8 





.42 


53 


30.5 « 




WNW 




Fair. 




2 





.48.4 


5t» 


30,51 




WNW 




Fine. 


7 


8 





. 43 


53 


30.45 




WNW 




Cloudy. 




2 





.42,5 


56 


30,37 




WNW 




Cloudy. 


8 


8 





38 


52,5 


30,25 




NW 




Cloudy. 




2 





.39,5 


53.5 


30,22 




WNW 




Cloudy. 


9 


8 





4P 


5a,5^^ 


30,08 




WNW 




Cloudy. 




2 





43 


53 


30,03 




WNW 




Cloudy. 


lO 


8 





.42,5 


53 


30,07 




NE 




Cloudy. 




2 





43 


54 


30,25 




E 




Cloudy. 


II 


8 





39 


52.5 


30,2a 




WSW 




Cloudy.. 


. 


2 





49 


55 


30,22 




W 




Cloudy.. 


12 


8 


c 


44 


53 


30,13 




W 




Cloudy.. 




2 





.50 


57 


30,17 




W 




Fair. 


^3 


8 





40^.5 


54 


30,42 




w 




Fine. 




2 





49 


58 


30.34 




w 




Cloudy. 


14 


8 





.42 


54 


30,18 




wsw 




Cloudy. 




2 





48 


56 


30,1.0 




WSW 




Cloudy.. 


15 


8 





.36 


53 


30,24 




w 




Fine. 




2 





45 


56 


30,23 


\ 


w 




Fine. 


i6 


8 


•0 


43'5 


53,5 


30,00 


\ 


Sby W 




Cloudy. 


i 


2 





..44 


5V 


29,95 




WSW 


« 


Cloudy. 



M.S.Xfi? 



f s 1 



— ^ n 

METBOEOLOGICAL JOURNAL 


for February 1 790. 




Time. 


Therm. 


Therm. 


Barom. 


Raio. 


Windi. 




*'V#\/\ 




without 


within. 








Weather. 


1790 


H. M.| „ 


e 


Inches. 


Inch. 


Points. 


Str. 


Fe*o.J7. 


8 


35 


54 


30,22 




WNW 


1 


Fnc.. 




2 


46 


56.S 


30,26 




WNW 


I 


Fair. 


18 


8 


3? 


. 54 


30^3 




WNW 


J 


Foggy. 




2 


46 


57 


30.45 




WNW 


I 


Fine. 


»9 


8 


40 


4 


30.49 




SW 


I 


Cloudy. 




2 


47 


58 


30.46 




SW 


I 


Fine. . . 


20 


8 


35.5 


53.5 


30,44 




N 


r> 


Foggy. 




2 


44 


57 


30.43 




N 


1 


Hazy. 


ai 


8 


33 


53 


30.40 




^ 


. 


Foggy- 




2 


40,5 


57 


2P,3^ 




NE 


I 


Hazyv 


23 


8 


37 


53 


30,22 




. NE 


< 


Fine. 




2 


.49 


STyS 


30,15 




SbyW 


I 


Fine. 


23 


8 


45»5 


55 


30,00 


o."5 


£ 


I 


Cloudy. 




2 


5o»S 


57 


30.00 




WNW 


I 


Cloudy. 


24 


8 


44 


55 


30.>7 




WNW 


I 


Cloudy. 




2 


50 


57 


30, » 7 




SW 


I 


Cloudy. 


as 


8 


49 


55.5 


30,04 




SW 


I 


Cloudy. 




2 


55 


5? 


30.11 




WSW 


I 


Cloudy. 


26 


8 


49 


55 


30,02 




. SW 


2 


Cloudy. 




2 


53 


58.5 


29,88 




SW 


2 


Cloudy. 


27 


8 


40.5 


S6 


30,23 




WNW 


2 


Fine. 




2 


50 


59.5 


30.49 




WNW 


2 


Fair. 


2b 


8 


42,5 


56 


30,25 




W 


X 


Cloudy*- 




2 


5° 


. 59.5 


30,25 




WNW 


1 


Fair. 




• 

















MS T B>> 



t «;] 







METEOROLOOICAL JOVRNAL 






for Much ty^o. 


• 


rime. 


Therm. 


Therm. 


Baroitt, 


Haitt. 


Wind.. • 1 








without 


within. 










1790 










, 






' Weither 


H. 


M. 










Inchei. 


Inch. 


Points. 


Str. 


▼f wAlUvl* 


Mar. 1 


/ 


46 


56 


30,35 
30,38 


NW 




Cloudy. 




a 





50 


58 




NW 




Cloudy. 


3 


7 





46.5 


56 


30,3a 




W 




Cloudy. 




2 





53 


Sj 


30,38 




NNW 




Cloudy. 


3 


7 





47 


56 


30.38 




NW 




Cloudy. 




2 





54 


59 


30.39 




NW 




Fair. 


4 


7 





40 


S5»5 


30,«8 




NW 




Fine. 




2 





49 


59 


30,27 




NW 




Fine. 


5 


7. 





40 


56 


3o,3t 




NNW- 




Clottdy. 




2 





46 


59 


30.39 
30,4* 




NNW 




Fair. • 


6 


7 


p 


36 


55 




N£ 




Fain 




2 





44 


57 


30,45 




NW 




Hit. ' 


7 


7 





40 


54 


30.44 




NE 




Cloady. 




2 





46 


' 57 


30,44 




N 




Cloudy. 


8 


7 





4« 


54 


30,44 


'' 


ENS 




Cloudy. 




2 





47 


55,5 


30.4a 




S 




ClouAy. 


9 


7 





39 


S3 


30,33 




W 




Cloudy. 




2 





50,5 


55.5 




w 




Cloudy. 


10 


7 





43 


33.5 


29,88 




w 




Fair. 




2 





$» 


56 


29,91 




w 




Fair. 


II 


7 





37 


53.5 


30,34 




w 




Fine. 




2 





S' 


56 


30,30 




w 




Clotidy. 


12 


7 





48 


^ 


30.30 


0,04a 


w 




Cloudy. 




2 





56 


5^ 


30,3a 




w 




fair. 


»3 


7 





50,S 


i6.5 


30,35 




w 




Cloudy, 




2 





^t 


58,5 


30,S«1 




w 




Cloudy. 


14 


7 





38 


55 


30,55 


0,080 


W 




Fine. 




2 





SO 


56 


30,52 




NW 




Fine, 


»5 


7 





35 


54 


30,59 




NNW 




Fine. 




2 





40 


55.5 


30,62 




N 




Cloudy. 


16 


7 





35 


53.5 


30*65 




NNE 




Fair. 




2 





46 


57 , 


30,6a 




NNE 




Fair, 



M B T E- 



i 7 ] 



WSTSOROLOGlCAi:, JOURNAL. 

'foi; March 1790. 



1790 



Mar. I 



18 



20 



21 



22 



2S 



25 

2^ 

27, 
28 

29 

30 



Time.jTherm. 
Iwithout 



H. W 



7 

2 

7 

2 

7 

2 

7 

2 

7 

2 

7 

2 

7 

2 

a4| 7 

2 

7 
2 

7 

2 

7 

2 

7 

1 

7 
2 

7 
2 

7 

2 



rhcrm. 

within. 




O 
o 
c 
d 
c 
o 
o 
o 
o 
o 
o 
o 
o 



.0 
o 
o 
o 
o 
o 



o 

Q. 
o 



o 
o 
o 
o 



3.1 

43.5 

3« 
47 
4a 
49 

3» 
48 

34,5 

•49 

J».5 

5 ',5 

40is 

50 

47.5 

5« 

4* 

54 

43 

53 

43 

55 

41 

S3 

4* 
48 

42 
4» 
4« 
Sa" 



5»,S 

5^.5 

53 

57 

54 

57f5 

54.5 

57 

54 

59 

53>5 

S».5 

54 

57 

54 

59 

55 

59 

56 

59 

55.5 

59 

5^,5 

$ 



1: 



rois. 



Inches. 



II I 



30,60 
30IS6 
30,46 

3^>44 
3^>4a 

3C^,40 

3o''33 
30,17 
30,06 
29,85 
19,85 
49,83 
29,84 
30 02 
30,06 
30,06 
30.05 
. 30>oi 
30,00 
30,06 
30,00 
30,00 
30,00 
30,00 

29>99 
29*9* 
a9>96 



Rain. 



Inch. 



Winds. 



Points. • Str 



NE 

£ 
NE 
N£ 
NNB 
NE 

£ 

E 
NE 

£ 
ENE 

£ 

E 
ENE 

E 

SW 

WSW 

SW 

E 

£ 

£ 
ENE 
ENE 

ENE 
NE 
NE 
ENE 
NE 
£ 



Weather. 



Fair. 

Ffnc. 

Cloudy. 

Fair. 

Cloudy. 

Fine. 

Fine. 

Finc^ 

Fine. 

Fine. 

Fine. 

Fine. 

Cloudy. 

Cloudy* 

Cloudy, 

Cloudy. 

Cloudy. 

Pair. 
Cloudy. 

Fair. 

Cloudy. 

Fair. 

Cloudy. 

Fair. 

Cloudy. 

Cloudy. 

Cloudy. 

Cloudy. 

Fair. 

Fine. 






METE- 



t « 1 



METEOROLOGICAL JOVKNALi | 




for April 1 790. 






Time. 


Therm 


Therm.' Barom. 


RaiD. 


Wind*, ] 








without 


within. 










1790 














Wuithcr. 


H. M. 





, iRcbe*. 


Inch. 

1 


Points. 


Str, 


April I 


7 


4* 


65 i 30.07 




£ 


2 


Fair. 




a 


44,5 


57 


30,08 




E 


2 


Fair. 


a 


7 


37 


5* 


30,26 




£ 


2 


Fine. 




a 


43 


57 




. E 


2 


Fine. 


3 


7 


35 


r 


30,30 




N 


2 


Fine, 




a 


48 


S0.«5 




NE 


2 


Fine* 


A 


7 


39 


li;l 


30,«3 




NE 


2 


Fine, 




a 


49 


30,22 




£ 


2 


fine. 


5 


7 


37 


54 


30,26 




NNE 


2 


Fair. 




a 


47,5 


58 


30,2a 




£ 


2 


Cloudx. 


' 6 


7 


40 


53.5 


30,08 




£ 


2 


Cloudy. 




a 


4? 


59 


30,00 




£ 


2 


Fair. 


7 


7 


38 


53 29,80 




NNE 


2 


Fair. 




2 


47 


59 


29,74 




£ 


2 


Fine. 


8 


7 


43 


5| 


29.69 




£ 


2 


Fair. 




2 


50 


58.5 a9.7i 




£ 


2 


Fine. 


9 


7 


40 


55 


29,62 




E 


2 


Cloudy. 




2 


47 


57 


29»55 




£ 


2 


Cloudy. 


lO 


7 


36 


53 5 29.46 


0,173 


ENE 


2 


Rain. 




2 


39.5 


50 


29,48 




NE 


2 


Cloudy. • 


II 


7 


li. 


53 


29.38 


0,024 


NE 


a 


Cloudy. 




a 


55 


29,44 




NNE 


2 


Snow. 


' 12 


7 


37 


53 


a9,40 


0.054 


N 


2 


Cloudy. 




2 


J^ 


54.5 


39,48 




N 


2 


Cloudy, 


»3 


7 


52,5 29,61 1 




N 


2 


Cloudy* 




2 


40,5 


55 


29,66 




NNE 


2 


Rain. 


14 


7 


37 


5* 


29,82 


0,140 


NW 


I 


Cloudy. 




2 


42,5 


56 


29,86 




NW 


2 


Cloudy. 


15 7 


36 


53 


29.76 




ENE 


I 


Rain. 


1 2 


42.5 


55,5 29.45 




ENE 


I 


Rain. . 


16 


7 


38 


52 29,7a 
55 29.87 


o,S93 


N 


I 


Cloudy. 




a 


43 




N 


I 


Cloudy. 



METE- 



[ 9 ] 





METEOROLOGICAL JOURNAL 






for April lygc. 




Time. 


Therm. 


Therm. 


iBaroai. 


Raio. 


Winds. 


^ 


I790 






without 


within. 








Wcathpr. 


•f** 
















H. 


M. 








Inches. 


Inch. 


Points. 


Str. 




Apriliy 


7 





35 


s* 


29,98 




NNW 


I 


Fine, 




a 





46 


56 


29,96 




N 


I 


Fair; 


l8 


7 





35 


5* 


30,01 




N 


I 


Fine* 




2 





46 


56 


30,02 




'E 


2 


Cloudy, 


»9 


7 





35,5 


5*.5 


30,05 




N 


2 


Fine, 




2 





45 


55.5 


30.05 




N 


2 


Cloudy. 


ao 


7 





39 


53.5 


30,29 




E 




Cloudy. 




2 





46 


56 


30,29 




E 




Fine. 


21 


7 





39 


5* 


30,24 




E 




Fine. 




2 





5° 


55 


30,20 




S 




Cloudy. 


22 


7 





46 


5'.5 


29,96 




EbyS 




Cloudy, 




2 





55 


55,5 


29,84 




S 




Fair. 


23 


7 





5' 


54,5 


29,72 




wsw 




Fair. 




2 





5! 


59 


29,66 




WSW 




Cloudy. 


24 


7 





48 


56 


29,49 


0,200 


SWbyW 




Cloudy. 




2 





53 


il 


29,50 




WSW 




Cloudy. 


as 


7 





45 


29,66 


9>035 


WSW 




Cloudy. 




2 





54 


■It 


29,63 




WSW 




Cloudy. 


26 


7 





44 


29,73 


0,025 


WSW 




Cloudy. 




2 





54 


59,5 


29,80 




sw 




Rain. 


27 


7 





42 


57 


29,98 


0,201 


N 




Cloud}^ 




2 





55 


59.5 


30,04 




N 




Cloudy. 


28 


7 





41 


56 


30,10 




NW 




Fine. 




2 





55 


59,5 


30,^ 




SW 




Cloudy. 


29 


7 





48,5 


57 


29,83 




8SW 


2 


Cloudy. 




2 





54 


58,5 


29,73 




ssw 


2 


Cloudy. 


30 


7 





^ 


57 


29,52 


0,025 


sw 


2 


Fair. 




2 





56 


59,5 29,62 




sw 


2 


Fair. 



Vol. LXXXI. 



METE- 



[ » 1 





t 

M^« T«'€)<R^O L O-GHtC A iL )J <0 tJ tR CN 4A C 




for M^ -ly^ro. 


Time. 


Therm" 


Theri»t 


wroni.i 


>R;ain.t 


WiiMk. 










without 


within. 
















. 










■ 


1790- 


H 


M. 





. -o. J 


lAiShds.. 


IiMJh.i 


P««ttts., 


Str. 


BMay i 


7 





48 : 


.56 s 


«9.63 




'S>£b}r £ 




Cleady. 




2 





S* ' 


•6b,5 


•29.IS 




•E e 




Raio. 


2 


7 





48 . 


:5fe.5 


•29.^0 


0,1)5 


«StV s 




Cloody. 




2 





57vS' 


<6«i 


: 29,6 1 


t 


-ftSlV r 




Faic 


3 


7 





47 ' 


:56 


T29,t6 


{ 


WSW V 




FaiK 




2 





■39^ 


^6(1 


:29,«7 


{ 


■NW I 




Fair. 


4 


7 





•47 


^56 


.30,04 


•i 


W t 




Fiia. 




2 





6« 


.6«t,5 


:3o,«4 


» 


, SW i 




FiBb. 


5 


7 





S^S 


;5fe.S 


:29,«2 
^29,88 




Mr i 




Clowljr. 




2 





■S5 .' 


.6b 


)j 


*&^<W5 




Clwidy. 


6 


7 





48 ^ 


:56«- 


'2:^,75 


o,ito< 


^W I 




Rab. ■ 


' 


2 





5« 


.6a 


29,72 




N ■> 




Rain. 


7 


7 





49 


6b ... 


0,280^ 


wi4\<rj; 




Cl«»dy. 




2 





'-i? -• 


-6g -; 


■a^.74 

a-9*«3: 


*\ 


E ,1 




Cl«mdy. 


8 


7 





S'l ? 


•6b!,5. 




■N t 




CIWKly. 




2 





•60^5 


6i3.5. 


■»9,83 


)* 


.•NKEr. 




Fain 


9 


7 





^■2 • 


•611 •; 


•J^,^8 


\{ 


.N 




Fino. 




2 





^59''5' 


64 . 


\ 


-N r 




Fair. 


10 


7 





5'iJS' 


.6te . 


je,oij 


a,o8^ 


■N t 




Cloudy. 




2 





58 


.6b ' 


.^0,<62 


)! 


..E .: 




CloBdy. 


II 


7 





^'i . 


6te 


•30,*6( 


' ^. 


>N ;• 




Clrady. 




2 





'H ■) 


•6jf 


130,46 


( 


,N t 




Fair. 


12 


7 


c 


5^ ; 


■6ti,S.' 


'50,09 




•SE <; 




Fins. 




2 





•6a 


66 ^ 


■5°'*9 


.< 


•N i. 


2 


Fine. 


'3 


7 





50 ' 


-611 ■ 


•30,14 


J 


>fJE ■ 


2 


Finew 




2 





Mis 


•64,3 


iifo.ii 




NE ;. 


2 


fine. 


14 


7 





50 • 


61 


'}o,lo< 


f 


'.N£ < 




FiM. ' 




2 





64 


66 


30,69 


I 


■K ,.' 




Fide. 


IS 


■7 


6 


50,5 


'61,5 


3oi03" 




Wf • 


"I •' 


Haxy. 




2 





61,5 


65 


29,99 




WNW 




Fine. 


16 


7 





54 


62 


29,91 




ESE 




Fine. 




2 





66 


64 


29,86 




£ 


2 


Fine. 



M S T S- 



I » V 



1 






. for ^y 1790. 




Tline." 


TBenn. 
without 


Within. 


Q^oiq. 


>K«n, 


r Wipd^^ ' 




1790. 






1 








W«ath«n 


H.M. 


• 


1 • 


iwAei. 


jinpli. 


: ?4Wtl. 


S.tr. 




May 17 


7 


6«.5 
64.S 
57 


129M 


1 


i^n 


a' 


Fine, 




2 


S3 


-*9.2^ 




|WSW 


2 


Fair. 


18 


7 


i» 


i 29.98 


0,130k 


, w 


I 


Fine^ 




2 


6Q- 


60 


1 29.88 




I w 


2 


QJoujIy. 


»9 


7 


. Si 


a 


r»9.7!6 




. s 


. 2 


Fin^ 




2 


.** 


'29»6i9 




. s 


i2 


Cloudy. 


20 


7 


SP 


. 59 


'29.717 


0,13* 


wsw 


.2 


?>w» 




2 


59^ 


60 


. »9.7I7 




wsw 


c2 


Cloudy. 


21 


7 


5P 


$9,9 


a9»9|6 




: w 




Fii»» 




2 


5St.j 


59'5 
58.5 


29.96 




w 




Cloudy* 


22 


7 


SSK5 


zt 


o,o33t 


1 s 




Clo«*ly. 




2 


SJ 


:!•* 




r S6 




Cloudy. 


«3 


7 
2 


t. 


«».84 


9%^^ 


wsw 
: s 




Cloudy, 
Cl«wiy. 


24 


7 


.8 


I 69 


r«9>ao 


0,2Q» 


. E; 




Rajiv 




2 


; *' 


(«9'3> 
,2^3s 




SbyW 


«2 


Cloudy. 


25 


7 


s 


' 60,5 


Q>209 


s 


. I 


Raiq. 




2 


' 69,5 


,*9'as 




NE 




Cloufly. 


26 


7 


SA 


61 


. 29.94 


0,011 


E 




Cloiv^. 




2 


H 


61 


29.98 




! B 


« * 


Clovyiy. 


27 


7 


ss 


61 


SP.00 


o,ni 


1 NW 




Cloudy. 




2 


.*st 


6*,5 


29,96 




[WNiW 


. I 


Fair, 


28 


7 


1 6,* 


30.00 


9,831 


, »fE 




Cloudy. 




2 


66 


6|>5 


29,98 




: SNE 


* 


Fair, 


29 


7 


II 


; 62,5 


29,99 


0,137 


£ 




Cloudy. 




2 


63 


30,02 




S 




Cloudy. 


30 


7 




63 


30'<>5 




W 




Clwidy. 




2 


63 


30.94 




wr 




Cloudy. 


31 


7 


6» 


i 29,97 


0,119 


WNW 




Clowly. 




2 


6J 


^iC 


:?°'?«. 




N 




Cloudy. 



b » 



METE- 



I '* ] 



METEOROLOGICAL JOURNAL | 




for June 1790. 




Time. 


Therm 


Therm. 


Baron. 


Rain. 


Wind$. 




1790 




without 


within. 








Weather. 


H. M. 








Inchei. 


Inch. 


Points. 


Str. 


June I 


7 


56 


62 


30,17 


0,022 


W 




Fine. 




2 


66 


62,5 


30,12 




SW 




Fair, 


2 


7 


60 


62,5 


30,16 




N 




Fair. 




2 


66,5 


64.5 


30,16 




N 




Fair. 


3 


7 


59 


^3 


30,16 




W 




Cloudy. 




2 


64 


^3 


30,07 




w 




Cloudy, 


4 


7 


59.5 


63 


3P>07 




w 




Fair. 




2 


65 


64,5 


30,08 




NW 




Fair. 


5 


7 


55 


62 


30,20 




WNW 




Fair. 




2 


63 


63,5 


30,16 




WNW 




Fair. 


6 


7 


56*5 


61,5 


30.17 




w 




Fine. 




2 


63 


62 


30,16 




WNW 




Fair. 


7 


7 


P 


61 


29,96 


0,040 


WNW 




Cloudy. 




2 


i 


63 


29,96 




WNW 




Fair. 


8 7 


61 


29,92 




wsw 


2 


Fine. 




2 


I 


61,5 


29,79 




ssw 


2 


Cloudy. 


9 


7 


61 


29,56 


0,060 


ssw 


2 


Fair. 




2 


61,5 


29,49 




ssw 


2 


Fair. 


10 


7 
2 


8 


60 
61 


29,58 
29166 




w 

s 


2 
I 


Fair. 
Rain. 


II 


7 


53 


60,5 


29189 


0.340 


NNW 


I 


Fair. 


12 


2 
7 


64 
55 


62 
60,5 


29.85 
29.98 




WNW 
NW 


1 
I 


Fair. 
Cloudy. 




2 


62 


62 


30.02 




NNW 


I 


Fair. 


^3 


7 


53 


60 


30.26 




N 


I 


Fine. 




2 


61 


62 


30,27 




N 


I 


Fair. 


14 


7 


56 


60 


30'33 




• 




Fine. 


■ 


2 


66 


62^ 


30,30 








Fine. 


>S 


7 


61 


61,5 


30.20 
30.28 




N 


I 


Fair. 




2 


67 


63'5 




E 


I 


Cloudy. 


16 


7 


54 


61,5 


30.24 




NE 


1 


Cloudy. 




2 


63 


62 


_ 30.19 




NE 


I 


Cloudy. 



METE- 



t '3 1 





M £ T E E QL 6 I C A L J 


U KN AL 






for June 1790* 


■ 




Time, 


Therm, 


Therm. 


Barom. 


Raio. 


Windi 


• 




1790 






without 


writ bin. 










Weather. 


H. 


M, 








Incbet. 


Inch. 


Point*. 


Str. 


June 17 


7 





il 


61 


30,08 




NE 


1 


Cloudy. 




2 





62,5 


30,01 




£ 


I 


Cloudy. 


18 


7 





58 


6t 


29,88 


0,051 


W 


I 


Fair. 




2 





68 


63 


29.94 




W 


2 


Cloudy* 


'9 


7 





59.5 


62 


30,00 




SW 


2 


Cloudy^ 




2 





69 


64 


30,01 




sw 


2 


Cloudy, 


20 


7 





60 


62,5 


30,23 
30.28 




wsw 


I 


Fair. 




2 





69,5 


65 




wsw 


2 


Fine, 


21 


7 





65 


65 


30.35 




wsw 


I 


Fine. 




2 





^ 


67.5 


30.35 




wsw 


I 


Fine. 


22 


7 





69 


67 


30,20 








Fine* 




2 





86 


73.S 


30,10 




ssw 


I 


Fine. 


23 


7 





71 


7» 


29,96 




w 


I 


Cloudy* 




2 





76 


72 


29,96 




w 


I 


Cloudy. 


24 


7 





60 


66 


29.98 




w 


2 


Fair. 




2 





68 


68 


29,91 




w 


2 


Cloudy. 


25 


7 





II 


65 


29,87 




wsw 


2 


Fair. 




2 





67 


29,87 




wsw 


2 


Fair. 


26 


7 





57 


d,s 


29,89 




w 


2 


Cloudy. 




2 





6«,s 


29,89 
29.96 




WNW 


2 


Fair. 


27 


7 





S 


64,5 


0,120 


NW 




Fair. 




2 





66 


30,02 




NW 




Cloudy. 


28 


7 





53 


63 


30,08 


0,075 


WNW 




Cloudy. 




2 





64 


65 


30,07 




W 




Fair. 


29 


7 





55 


63 


30,02 




SW 




Cloudy. 




2 





69.5 


63.5 


29.97 




SSE 




Cloudy. 


30 


7 





II 


63 


*9»93 




SW 




Cloudy. 


1 


2 





-Ji- 


29,91 




SW 


2 


Cloudy. . 



METE* 



t »♦ 1 





^l^r VCMtOL dOIPC Jt& jaVK2»AEi H 






.f«rjulf 179a;. 1 




Time. 


Therm. 


Tfhcrm. 


Baroin, 


ftam. 


Wi|RK« 


1 ■ " " ""T •• ■ 








without 


udthiQ. 








1 


1790 






"* 




. 




' 


TRbatBeTii 


H. 


M. 


. ' 





I?a«ft<»„ 


loclt. 


Fbitifi. 


^tr. 


July 1 


7 





«o 


fSnS 


t^i"* 


0,04a 


'WSSM 


2f 


CloiiK^. 




2 





■W 


: i* 


«9.83 




[wsw 


^ 


Hair. 


2 


7 





S6-.S 


% 


29.7a 


t 


■wsw 




flair; 




2 





^3 


e3«s 


i^bi 




> sw 


; t 


Aaiif. ' 


3 


7 





54.5 


^ 


0,08a 


= w 




Hiiii% 




2 





TO- 


; ?* 


. 25.68 




tWJW 




Qioudlr. D 


4 


7 





SS 


^ 


,29»3a 




8W 




Bair. ^ 1 


5 


2 

7 






6fr 


64 


o.o«jf 


8swr 


' 2i 






2 





67,5 


63*5 


29>29l 




w 




Clootly. 


6 


7 





5S 


62^ 


.29*64 


0,153 


- NW 




Cloothr, 
CloiK^. 




2 





6^5 


' l?"^ 


29,80 




;nnw 




7 


7 





5S 


(n 


30,10 


0,014 


• N 




Bine; 




2 





67 


^3 


30.16 




• NW 




Bair: 


8 


7 





55 


e% 


30,2a 




= srw 


' t 


Bair; 




2 





^ 


^*S 


- 3D'i4 




ar«r 


' t 


Cloudjr* 


9 


7 





58 


^ 


29M 


0,320 


S1^ 


1 q| 


Clowfy. 




2 





67- 


, 6-4 


29,7a 




SW 




Bair. 


10 


7 





SS 


!3 


29,82 


0,090 


' V9f 




Cloudjr, 




2 





f>s 


^3 


29>78 




!WSW 


t ^ 


Cknidy. 


II 


7 





r 


«2 


,29>SS 


' 


' W 




Cloiw^. 




2 





O3 


29,08 
29,6;]l 




NMW 


( f 


Clo«dy. 


12 


7 
2 






ii 


&I.5 
62,5 


6,069 


W 


^ I 


Cloudy. 
Clo»<fy. 


13 


7 

2 







ts 


di,5 
62,5 


29.60 
29*46 


0,063 


83W 


< J 




14 


7 
2 






a 


61,5 

'. 6a 


29.51 
29»ss 


o,aoj 


W 


\ Y 


Cloudy. 


15 


7 





SS 


61 


29'7S 


0,050 


w 




Fine. 




2 





68 


6i,s 


29.84 




w 




Cloudy. 


16 


7 





S8.S 


61 


29.95 




w 




Fair. 


'2 





69 


62,5 


30.03 




NW 




Fair. 



MB T E- 



I 'J 1 



• 

Jl E V BO R LO'O JiC A.I. )J iP V 01 iN jll f. 


for July 1790. 




Time/ 


Therm. 


Therm. 


Baroin.. 


B«m.; 


WUMk. 




1790, 




without 


•rithin. 






.• 




ri. ]V[. 





to ■ 


iMClu*.. 


IiKii.. 


PeiDts., 


Str. 


July 17 


7 


61 ^ 


,6fc 


,30,16: 


1 


NW , 




Cloody. 




2 


70 i 


r6B.5 


;30,i6 


t 


Vff , 




Cloudy. . 


18 


7 


*64 , 


.%' 


30,08 


i 


w . 




Cloody. 




2 


ja » 


-6H ' 


?o,©4 


' 


>8W : 




Clmdy. 


»9 


7 


!«9 > 


61+ .'. 


ISP,©*- 


Q»06o 


^W i 




Fine. 




2 


J« 1 


.* 


'30»«4 




W . 




Fine. 


20 


7 


«l 


'6)3.5 


.■29,80! 


0^<»ifi: 


6W 


12 


Cloody. 




2 


t6^^.5 


a9.*3 




-8W ^ 


)2 


Olndy. 


21 


7 


S; 


•6)3.5 


n9.r7 


o,oi6( 


W , 


;2 


Fair. 




2 


•64 


A9,86 


.t 


WNW. 


;a 


CloMdy. . 


22 


7 


:<« > 


r6B 


<3o,«6 




•w t 




Cloudy.. 




2 


7<?«S. 


.64 


'3©,c6 


. 


WNW 




Bair. 


23 


7 


!*9 J 


.6b 


■■3f>,^i 


9^015 


*VNWf 




ClQady.. 




a 


'«9 > 

>42 ', 


.63,5 


129,99 




W - 




Rain. 


24 


7 ^ 


•6i3.5 


/30,«o 


0,060 


W^NW; 




Cltualy. 




2 


•7-1 ; 


■6l5 


^30,03 


» 


WNW, 




ClQi«ly, 


25 


7 


a» i 


.e«+ . 


•3«>.»3 




WNW- 




Gloody. 




2 


74*5 


•6IS.5 


-30,14 


( 


^W .' 




FilDB. 


26 


7 


59 : 


•^ 


'30,16 


■' 


WSW 




CUwdy^ 




2 


78.5 


6|S,5 


•'30. »4 


)i 


w .. 




Bair. 


27 


7 


.*9 


: 614.5 


'30. *5 




W ;' 




Cloudy. 




2 


.7^5 


.616,5 


/30.15 




WNW 




Fair. 


28 


7 


5«it5 


..6iS 


30,10 




• E .' 




Cloudy.. 


1 

29 


2 
7 


1& • 


6!5.5 


•9.96 
£9,60 


t 


WW ,' 




FiBB. 
CloKdy. 




2 


.65.5 


.'a9»l;8 


( 


.«w 




Cloudy. 


30 


7 


55 


614 ' 


a9,6o 


o,ojjo 


w 




Cloudy. 




2 


dfta 


M 


'29.64 


, 


w 




eiaudy. 


31 


7 <^ 


56 


;6|3.S 


;«9,a6 


0,303 


wsw • 


■a 


Cloudy.. 




2 


(>f 


•^J 


:a9,6i 




wsw 


a 


Cloudy.. 





















M B T. S«.^ 



I •« 1 



• : 


METBOROLOGICAL JOURNAL 








for Auguft ] 


790. 




Time. 1 


Therm. 


Therm. Barom. 


Rain. 


Windi. 








without 


within. 




¥ ttf\/\ 
















Weather. 


1790 


H. 


M. 


• 


• 


laches. 


Inch. 


Pointi. 


Str. 


Aug. I 


7 





S3 


63 


29.93 


0,012 


W 




Pine. 




2 





66 


64.5 


30,00 




W 




Fair. 


2 


7 





56 


6»,5 


29,91 




sw 




Cloudy. 




2 





59 


62,5 


29,81 




ssw 




Rain. 


3 


7 





55 


62 


29.74 


0,202 


wsw 




Cloudy. 




2 





65 


62,5 


29,66 




w 




RaiD. 


4 


7 





67.S 


61,5 


29.83 


0,081 


w 




Cloudy. 




2 





62.5 


29,86 




w 




Fair. 


5 


7 





55 


61,5 


30,04 




w 




Cloudy. 




2 





69 


62 


30,00 




w 




Cloudy. 


6 


7 





60 


62 


29,91 




w 




Cloudy. 




2 





66,5 


63,5 


29,86 




wsw 




Rain. 


7 


7 





64 


63.S 


30,01 


0,025 


wsw 




Cloudy. 




2 





76 


65 


30,01 




w 




Cloudy. 


8 


7 





62 


65 


29,88 




w 




Cloudy. 




2 





7> 


66 


29,94 




w 




Cloudy. 


9 


7 





57,5 


64,5 


30,00 




WNW 




Fine. 




2 





70 


66 


30,00 




NW 




Fine. . 


10 


7 





56.5 


64.5 


30.07 




w 




Fine. 




2 





75.5 


67 


30,06 




w 




Fine. 


II 


7 





56»S 


65 


30.14 




w 




Hazy. 




2 





75 


67 


30, » I 




w 




Hazy. 


12 


7 





58 


66 


30* » I 




wsw 




Fair. 




2 





73 


67 


'30,10 




sw 




Cloudy. 


13 


7 





60,5 


67 


30.04 




w 




Fair. 




2 





74 


68 


30,02 




w 




Cloudy. 


14 


7 





60 


6?,s 


30,10 




WNW 




Fine. 




2 





7*.5 


30,10 




NW 




Fine. 


JS 


7 





59 


67 


30,02 




SSE 




Fine. 




2 





75.5 


69»S 


29.95 




SSW 




Fine. 


16 


7 


c 


66 


68 


29.90 




WSW 




Cloudy. 




2 





21., 


69 


29.93 




wsw 




Cloudy. 



M S T S- 



t »7 1 





M 


ETEOROLOGICAL JOURNAL 










for Auguft 1790* 






Tunc. 


i hcrm. 


ritcriii 


Bar cm. 


Raui. 


Winds* 












without 


within. 












* ««/>/N 
















* Weather. 




1790 


H. 


M 








Inches. 


Inch. 


Points. 


Srr. 




Aug. 1 7 


7 





60 


68 


^9*95 


0,020 


VV 




Fair. 






2 





68 


68,5 


30,01 




WNW 




Raid. 




18 


7 





60 


68 


30,16 


0,061 


WNW 




Cloudy. 






2 





7» 


68 


30*13 




WNW 




Fair. 




»9 


7 





59 


67 


30»02 




W 




Cloudjr* 






2 





7'.S 


68 


30.00 




w 




Cloudy, 




20 


7 





03 


67.5 


30,05 




w 




Cloudy. 






2 





77 


69.5 


30,05 




wsw 




Fine. 




ai 


7 





;i 


68 


29,78 


0,060 


SSE 




Fine. 






2 





73 


29.73 




w 




Hazy. 




22 


7 





56 


68 


30,04 




w 




Fine. 






2 





67 


68 


30,08 




w 




Fine. 




«3 


7 





62 


67 


29»94 




wsw 




Cloudy, 






2 





67 


67.5 


29^94 




wsw 




Cloudy. 




^4 


7 





U 


65.5 


30,01 




w 




Fine. 






2 





66,5 


29^96 




w 




Fair. 




as 


7 





53 


64 


29,93 




w 




Cloudy. 






2 





S9»5 


64.5 


'29.85 




S£ 




Rain. 




26 


7 





57 


64,5 


29,64 


1,150 






Rain. 






2 





63 


65 


29»73 




MW 




Cloudy. 




a? 


7 





55 


64 


29,83 


0,03s 


NW 




Cloudy. 






2 





58.5 


64 


2(;,8o 




N 




Cloudy. 




28 


7 





5»>5 


6a 


29,9s 


0,345 


WNW 




Cloudy. 






2 





63 


63.5 


^9»95 




W 




Cloudy. 




29 


7 





53>5 


62 


30,02 




w 




Cloudy. 






2 





59 


62 


30*04 




w 




Cloudy. 




30 


7 





I', 


61,5 


30,15 




w 




Cloudy. 






2 





62,5 


30,15 




wsw 




Fair. 




31 


7 





59 


62 


30,08 




wsw 


2 


Cloudy. 


J 




2 





73 


64 


30,06 




w 


2 


Cloudy. 


-J 



Vol. LXXXI. 



M BT B* 



C r8 I 



METEOROLOGICAL J O U R H A I 






for September 1790. 1 


• 


Time. 


Therm, 
without 


Therm, 
within. 


Birom.- 


Rain. 


Winds. 


r 


1790 














Weather. 










* 






H. M. 





e 


^ncbes. 


inch. 


Points. 


Str. 




Sept. 1 


7 


6a 


63.5 


29,88 


• 


W 




Cloudy. 




2 


68 


64 




W 




CUmtly. 


2 


7 


r 


62,5 


29.82 




W 




Fair. 




2 


62,5. 


29,60 




w 




Cloudy. 


3 


7 


49'5 


61 


29,31 


0,2l6 


w 




Fine. 




2 


58 


64,5 


29.43. 
29.04 




w 




Cloudy. 


4 


7 


48 


60 




WNW 




Fine. 




2 


61 


62 


29,64 




w 




Cloudy. 


5 


7 


4S 


S9.5- 


29.67 




w 




Fine. 




2 


^^ 


bi 


29.77 




WNW 




Fair. 


6 


7 


59 


30,60 




N 




Fine.^ 




2 


6o 


60 


30.03 




NNW 




Fair. 




7 


46 


5^*5 


30. tl- 




NNW 




Fine. 




2 


55.5 


60 


30.05 




N 




Rain# 


8 


7 


49! 


S8,5 


30,06 


0,082 


Nby W 




Fine. 


, 


2 


58 


6i,S 


30,12 




NNW 




Fair. 


9 


7 


49 


58.5 


30,19 




W 




Cloudy, 




2 p 


62,5. 


59'5 


30,1a 




w 




Fair. 


10 


7 


57 


59 


19,96 


0*053 


w 




Cloudy, 




2 


64 


60 


29,98 




w 




Fair. 


II 


7 Q 


it 


59'5 


29,98 




w 




tine. 




2 


61 


30,04 




tv 




Fair. 


12 


7 


55-5 


59.* 


30,11 




w 




Cloudy. 




2 


63^ 


50.5 


30,1 J 




w 




Cloudy. 
Cloacjy. 


»3 


7 <^ 


?5'' 


6o,s 


3o,Qb 




w . 






2 


bi 


29,94 




w 




Fair. 


H 


7 


f^ 


61,5 


29,86 




ssw 




Cloudy* 




2 


62,5 


29,75 




sw 




Fair. 


15 


7 


1? 


hi 


29,78 




ssw 




Cloudy. 




2 


63.5 


29.75 
29,98 




ws"\V 




Fair. 


16 


7 


49 


61,5 




wsw 




Fair. 




2 


62 


62,5 


30,10 




w 


■ » 


Fine 



ISBTk- 



I «> ] 







Ad 


[ETEOROLOG 


- I C A L J 


U R N A I. 






for September 1790. 




Xifuc. 


.Therm. 


rhtriu. 


Bsrom. 


Ram. 


Wmds, 


Weather, 


1790 






without 


'.viibin, 








H. 


M. 





c 


Inches. 


Iiidi. 


Points, 


Str. 


Sept, 17 


7 





48 


61 


30.33 




W 




Fain ' 




2 





63 


63 


30,26 




svv 




Fine. 


18 


7 





46.5 


61 


30. > 5 




sw 




Fine, 




2 





68 


64 


30,08 




sw 




Fine. ' 


»9 


7 





S6 


6^5 


29,85 




sw 




Cloudy. ' 1 




2 





68 


^5 


29.72 




sw 


2 


Fair. 


flo 


7 





5a 


°3»5 


29,64 


o.oao 


wsw 


2 


Fine, 




2 





63 


64 


29,68 




w 


2 


Fine. 


2t 


7 





5° 


*o.S 


29.83 




w 


2 


Fine, 




2 





59 


6'.S 


*9i99 




■WNW 


2 


Cloudy, 


22 


7 





47 


59 


30,23 




w 


I 


Fine, 




2 





H^s 


60, S 


30.20 


<■ 


ssw 


i ^ 


Cloudy, 


93 


7 





1? 


60 


29.90 




ssw 


2 


Cloudy. 




2 





66 


61.5 


29.90 




w 


2 


Cloudy. 


84 


7 





55 


6i,s 


30.a5 


0,063 


^NW 


a 


Cloudy, 




2 





61 


6r,5 


30.34 




NW 


2 


Cloudy. 1 


as 


7 





53 


60 


30.38 , 




KW 




Cloudy. 




2 





60 


61 


3°.i5 




NW 




Cloudy. 


36 


7 





4« 


59,5 


30,42 




WNW 




Cloudy, 




a 





60 


60 


30.42 




N 




Cloudy. 


«7 


7 





5? 


59 


30»3& 




NE 




Fair. 




a 





S6 


59 


30.30 




ESE 


J 


Cloudy. 


28 


7 





4a 


58 


30,14 


' 






Foggjr. 




2 





56.J 


59 


30.05 




W 




Fine. 


29 


7 





5° 


58 


30,17 




N 




Cloijdy. 




2 





59.5 


59 


30,22 




N 




Fair. • 


30 


7 





Sa.5 


58 


30,15 




-NE 




Cloudy. ^ 




2 





59.5' 59.5' jo.aol 




E 


1 jFair. | 



c a 



^M E T X"^ 



C ?<» I 



1 
MBTpOROLOGICAL J&URNAl, 




for Odober 1790. 




Time. 


Therm. 


Therm. 


Barom. 


Rain. 


Winds. 




1790 






without 


within. 








Weather. 


H. ] 


M. 





• 


Inches. 


Inch. 


Points. 


Str. 


Oa. 1 


7 





46 


58 


30.03 


E 




Fine., 




2 





57 


59.5 


29.95 




E 




Fine. 


2 


7 





49 


58 


29,80 




ENE 




Cloudy^ 




2 





60 • 


60 


29.78 




£ 




Fine. 


3 


7 





.56 


59 


29.77 


0,083 


£ 




Cloudy. 




2 





64 


00 


29,82 




S 




Cloudy. 


4 


7 





5 1. 5 


59 


29,90 


., 


N 




Cloudy. 




2 





57 


59 5 


29.95 




W 




Cloudy. 


5 


7 





52 


59.5 


30,0b 


0,401 






Foggy* 




2 





60 


60,5 


30,00 




W 




Fair. 


6 


7 





'54 


60 


29,80 


0,132 


sw 




Cloudy^ 




2 





62 


62 


29,80 




sw 




Fair. 


7 


7 





.56 


60,5 


29,78 


0,035 


SSW- 




Cloudy, 




2 





'. 64,5 


63 


29,76 




sw 




Fine» 


8 


7 





•SI 


61,5 


29,84 




WNW 




Fine. 


• 


2 





. 59 


63.5 


29,89 




WNW 




Fine, 


9 


7 





52 


61,5 


29,89 


0,101 


N 




Cloudy. 




2 





54,5 


.^V 


29,94 




NNW 




Fine. 


xo 


7 





. 40 


30.09 




NE 




Fine. 




2 





50.5 


59 


30.08 




N 




Hazy. 


II 


7 





39 


i6,5 


30," 




N 




Foggy. 




2 





53»5 


59 


30,07 


. 


SSW 




Fine. 


12 


7 





51 


57 


29,86 




yf&w 




Cloudy. 




2 





58 


57.5 


29,66 




sw 


2 


Cloudy. 


»3 


7 





53 


56.5 


29.71 


0,073 


sw 


2 


Fine. 




2 





55>5 


5* 


29,79 




w 


2 


Fine 


14 


7 





1* 
04,5 


56 


«9,8o 




sw 


2 


Cloudy. 




2 





59.5 
58.5 


29.79 
29,98 




sw 


- 2 


Cloudy. 


»5 


7 





53.5 




wsw 


2 


Fair. 




2 





62 


60,5 


30,00 




w 


2 


Cloudy. 


16 


7 





45 


1* 


30.34 




w 


I 


Cloudy. 




2 





.-53.5 


60 


30,40 




£ 


I 


Fine. 



M B T X- 



[ 2» ] 



] 


[4ETBOROLOGICAL J 


U R N A L 






for OAobsr 1790. 


- 




Time. 


Therm. 


Therm. Baiom. 


Rain. 


Wincis 






f *l/\n 






without 


wirhin. | 








Weather. 


1790 


H. 


M. 





g Inches. 


Inch. 


Points. 


6tr. 


oa. 17 


7 





.46 


57.5 -3^.20 


■ 


£ 


I iFinc. 




2 





57 


60,5 


30,01 




SSE 


1 Fine. 


18 


7 





• 55 


58 


29,89 




sw 


2 Cloudy. 




2 





■55 


bo,5 


29,86 




W 


I ,Rain. 


^9 


7 





39 


57.5 


30t«7 


0,263 


w 


I 


Fine. 




2 





SO 


60 


3o»io 




w 


I 


Fine. 


20 


7 





4» 


57 


30|0S 




£ 


I 


Fine. 




2 





55.5 


59-5 


29,96 




£ 


I 


Hazy. 


21 


7 





52 


58 


29*93 


0^20 


£ 


1 Rain. | 




.2 





60,5 


6a 


29,87 




£ 


I 


Fine 


22 


7 





54 


60 


a9»7S 




£ 


I 


Cloudy. 




2 





62 


62,5 


29.70 




£ 


I Cloudy. 1 


a3 


7 





5? 


60,5 


29,72 




E 


I 


Cloudy. 




2 





•59.5 


62,5 


29162 




£ 


I 


Cloudy. 


24 


7 





5» 


60 


29,72 




SW 


I 


Cloudy. 




2 





55.5 


6a,5 


29,72 




W 


I 


Cloudy. 


25 


7 





5? 


60.5 


29,70 




WNW 


I 


Cloudy. 




2 





56 


62,5 


29,77 




WNW 


I 


Fair. 


26 


7 





49 


60 


29,90 




NE 


1 


Cloudy. 




2 





56 


62 


29,90 




NE 


I 


Cloudy. 


27 


7 





46,5 


60 


2985 




NE 


2 


Cloudy* 




2 





•49 


58.S 


29,83 




NE 


2 


Cloudy. 


28 


7 





.46 


58 


29,60 




£ 


I 


Cloudy^ 




a 





.48 


60 


29.67 




£ 


I 


Cloudy. 


29 


7 





.46 


,8 


29,77 




E 


2 


Cloudy. 




2 





48 


60 


29,83 




£ 


2 


Fair. 


30 


7 





43 


57 


29,84 




NE 


1 


Cloudy. 




2 





45 


57.5 


29*83 




NE 


2 


Cloudy. 


31 


7 





40 


Ik 


29,86 




NNE 


1 


Cloudy. 




2 





45 . 


29,90 




N 


I 


Cloudy. 



If E T X« 



I « 1 





M9TSOXOXOOICAL JOURNAL 




for November 1790. 




Time. 


Tkcihn. 


Therm. 


[Barom. 


Rain. 


Wind*. 










without 


within. 








Weather, 


1790 


H 


M. 





. 


laches. 


loch. 


PuiDts. 


Str. 


Nov, I 


7 





43 


S4 


a9.83 




SE 


2 


Cloudy. 




a 





50 


S6,J 


29*66 




S 


2 


Rain. 


41 


7 





45 


S4.!5 


19.34 


0,619 


W 


I 


Cloudy. 




2 





Sa 


58 


29.48 




W 


2 


Cloudy. 


3 


7 





41 


S4>iS 


29,80 




- W 




Fine. 




2 





SO 


58,5 


a9.78 




w 




Cloudy. 


4 


7 





44 


iLS 


39,69 


0,170 


w 




Fine. 




2 





u 


59 


39»70; 




w 




Fine. 


5 


7 





56 


»9.95 




w 




Fair. 




2 





52.S 


.58 


a8.94i 




s 




Cloudy. 


6 


7 





SI 


57 


29.74' 




. E 




Cloudy. ' 




2 





^3 


58 


29,68 




bSE 




Rain. 


7 


7 





44 


56 


29.64 


0.057 


£ 




Cloudy* 




2 





47 


57 


29,66 




£ 




Cloudy. 


8 


7 





40 




J^9»85 




£ 




Fine. 




2 





48 


58 


29,87 




£ 




Fine. 


9 


7 





43 


S6 


30.04 


I 


NE . 




Cloudy. 




2 





47 


58 


30.09, 


j 


ENE 




Cloudy. 


10 


7 





.42 


5S>5 


30,2a 




ENE 




Cloudy. 




2 





46 


57 


30,06 




ENE 




Cloudy, 


11 


7 





47 


56 


29,96 


. 


NE 




Cloudy. 




2 





.48 


57 


30,03 


1 


NE 




Cloudy. 


4a 


7 





47 


5^ 


30.1 1'l 




NE 




Cloudy. 




2 


•0 


47ii 


S7.S 


30, If 




NE 




Cloudy. 


^3 


7 


x> 


4« 


r 


30,16 




NE 




Cloudy. 




2 





52»S 


30.19 


i 


■NE 




Fine. 


M 


7 





.43 


55 


30.27 




NE 


■I 


Cloudy. 




2 





47 


57 


30.26 




NE 




Cloudy. 


X5 


7 





40 


S4>5 


30.30 




NE 


2 


Cloudy. 




2 





M 


56 


3027 




NE 


2 


Fine. 


16 


7 





35'S 


53 


30,16 




NE 


2 


Fine. 




2 





43. 


55 


30." 




ENE 


2 


Fine. 



M £ T S- 



r «3 I 



J 


METEOROLOGICAL JOURNAL | 




for Novembei 


• 1790. 




Time. 


Therm. 


Therm* Barom. | 


Rain. 


Winds. 










without 


within. 








Weather. 


1790 


H. 


M. 








Inches. 


Inch. 


Points. 


Str. 




Nov^i? 


7 





40.S 


53 


49.98 




ENE- 


L 


Cloudy. 




2 





43.S 


5S.S 


29,91 




ENE 


2 


Fair. 


18 


7 





34 


52.5 


29,71 




W 


1 


Cloudy. 




2 





38 


53>5 


*9.55 




sw 


I 


Fair. 


^9 


7 





46 


53 


a9.'3 




s 


2 


Rain. 




2 





44 


5S 


29,10 




ssw 


2 


Cloudy. 


20 


7 





:i 


53 


29,16 


0,295 


s 


2 


Fine, 




2 





56 


29,21 




s 


2 


Rain.. 


21 


7 





44 


53 


29,02 


0,150 


sw 


2 


Fair. 




2 





48 


57 


29,10 




sw 




Rain. 


22 


7 





48,5 


54 


29,27. 
29.38' 


0.950 


s 




Clowly. 




2 





58,5 




N 




Cloudy. 


23 


7 





46 


55 


29,61 


0,115 


N 




Foggy. 




2 





48 


58 


29>68 




SW 




Cloudy. 


24 


7 





3S 


54 


29,83 




SW 




Cloudy. 




2 





44,5 


56 


29,85 




W 




Fine. 


*s 


7 





47 


54,5 


29,7s 




&w 


2 


Cloudy. 




2 





50 


57 


29,58 




s 


2 


Cloudy, 


26 


7 





tt 


55 


29,48 


0,156 


wsw 




Cloudy. 




2 





. 57.5 


29»74 




ENE 




Cloudy. 


a? 


7 





36 


54 


30,21 




NW 




Fine, 




2 





42 


57 


30,28 




NW 




Cloudy. 


28 


7 





37 


53»S 


30,40 




N 




Pair. 




2 





43 


58 


30»34 




E 




Cloudy, 


^9 


7 





34>5 


53 


2P>H 




£ 




Cloudy,. 




2 





35 


54»5 


30,05 




E 




Cloudy^ 


30 


7 





3a 


50 


29,72 




£ 




Cloudy* 




2 





34 


^Slt^. 


.2a'6* 




E 




dloudy. 



M B T S- 



t 84 ] 



^ 












^ . 


- 








METEOROLOGICAL JOURNAL 




for December 179:?* 




Time. 


Therm. 


Therm. 


Uaroin. 


Rain. 


Winds. 










without 


within. 










1790 





'^'"* 












Weather. 


' 
















H. 


M. 






,_ 


Inches. 


Inch. 


Poiat». 


Str. 




Dec. I 


8 


32 


49 


29,64 




ESE 


1 


Cloudy. 




2 





32 


50.S 


29,22 




E 


2 


Snow, 


3 


8 





43 


51 


29.3' 




WNW 


2 


Cloudy. 




2 





46 


54 


29.59 




WNW 


2 


Fair. . 


3 


8 





42.S 


52 


29.85 




S 


I 


Rain. 




2 





50 


55 


29.5» 




ssw 


2 


Cloudy. 


4 


8 





42 


53 


29,94 


0,220 


w 


I 


Cloudy. 




2 





44 


56 


29.97 




w 


I 


Cloudy. 


5 


8 





37 


52 


29'9' 




•WNW 


1 


Cloudy. 




2 





4* 


56 


30,00 




WNW 


I 


Cloudy. 


6 


8 





36 


52 


30,36 




NW 


1 


Cloudy. 




2 





41 


56.5 


30,38 




NW 


I 


Fine. 


7 


8 





38 


5i»5 


30'33 




W 


I 


Cloudy. 




2 





■43.S 


54.5 


30.24 




W 


I 


Cloudy. 


8 


8 





47 


54 


30»*5 


0,105 


NW 


I 


Cloudy. 




2 





48 


57 


30,18 




N 


I 


Cloudy. 


9 


8 





47 


54.5 


3(5.1 8 


0,023 


NNW 


I 


poggy- 




2 





48,5 


57»S 


30.15 




WNW 


I 


Cloudy. 


10 


8 





47 


56 


30.^9 




W 


X 


Cloudy. 




2 





50 


'58.5 


30.19 




W 


I 


Foggy. 


11 


8 





49 


56.5 


29,96 




w 


2 


Cloudy. 




2 





52 


58 


29,85 




sw 


2 


Rain. 


12 


8 





47 


54>5 


30,06 


0,015 


w 


I 


Fine. 




2 





43.S 
46,5 


58.5 


30,08 




' w 


1 


Fine. 


'3 


8 





55'5 


29,86 


0,028 


w 


2 


Cloudy. 




2 





48 


58 


29.55 




. ssw 


2 


Cloudy. 


14 


8 





391 


55 


29.85 


0.444 


' w 


2 


B'xnt. 




_2 







•5M- 


. 3Q»QP 




WNW 


2 


Fine. 


»5 


8 





46 


55 


29»33 


0,082 


NW 


2 


Cloudy, much wind laft night 




2 





48 


57 


29,40 




w 


2 


Fair. 


16 


8 





38 


54 


29,70 




w 


I 


Cloudy. 




2 





42 5S«5l 


29.36 1 


s 


I 


Rain. 



M B T E- 



[ 25 ] 



METBOROLOOICAI. JOURNAL 

for December 1790. 



rrime. Therm, 
without 



1790 



H. M. 



Dec. 17 
18 

19 

20 

21 
22 

*3 
24 

26 

27 

a8 

29 
30 

3» 



8 

2 
8 

2 

8 

2 
8 
2 
8 
2 
8 

2 



O 
O 
O 

I 

o 
o 
o 
o 
o 
o 



8 o 



o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 
o 



39 

43 

38 

39 

3I»S 

33 

33 

34.5 

43 

50 

38 

43 

38 

43.5 

37 

42 

44 

44 

33 

3S.5 

3? 
38 

33>5 

36,5 

30 

3a 

37 

3' 

3< 

4> 



Therm 
within. 



Inches. 



r 



JO 

1,5, 



5* 

53»5 

5 

S3 
SO»S 
53 
50. 
S3 
5^5 
. S4,5 

52 

54 
52 
S4>5 
S3»S 

54 

52 

53»S 

49 

53r5 

SO 

^^ 
48,5 

5^5 
48 

S? 
48 
5^5 



Barom, 



Inch. 



Ram. 



0,185 



0,070 
0,136 



29,37 0,220 
29*24 

28,8a|0|io7 

29»'5 

29»S5 

29.»5 

29,90 

30,06 

29,90 

29.7? 
30,06 

301I7 

29>74 

29,87. 

30*24 

30,17 
30,00 0,133 
30,08 

30,24 
30,22 

30,04 
29,90 
29>97 
30,07 
30,25 
30,22 

29,94 
29,84 
30^02, 
30, H' 



Winds. 



Fobts. Str 



Oy020 



0,305 



wsw 
sw 
w 
w 

sw 

S£ 

SW 

WNW 

SW 

ssw 

w 

w 

w 

w 
w 

sw 

NW 
N 

w 

sw 

wsw 

sw 

WNW 

NNW ' 
N 

wsw 

s 

ssw 

N 
N 



Weather. 



1 Fine. 

1 Cloudy. 

2 aoody, much wind lai| iught.| 
2 Cloudy. 

1 Fine. 

2 Snow« 
I Fine. 

1 Fine. 

2 Cloudy« 
2 Rain. 
2 Fiqe. 
2 Fine. 

r Fair, much wind, thunder, 
I and lightning laft night. 
Fair. 

Foggy. 

Cloudy. 

Rain. 

Cloudy, 

Foggy. . 

Cloudy, 

Fair. 

Cloudy. 

Fine. 

Fine. 

Fine. 

Fine. 

Cloudy. 

Cloudy. 

Cloudy^ 

Cloudy, 



Vol. LXXXI. 



1790 



[ 26 ] 





Therm without 


.1 Therm, within. 


1 Barometer. 


Rain. 


1790 


s « 


Jl 

03 


• Mean 

height. 

Greateft 

' heieht. 


II 


^ 


Greateft 
height. 


Leaft 
height. 


Mean 
height. 






o 

















Inches. 


Inches. 


Inches. 


Inches.. 


January 


52.S 


3* 


40,9 


56,5 


50 


53.1 


30.47 


29,37 


30.07 


.0,967 


February 


55 


3.3 


43»8 


59.5 


52 


54.9 


30,6a 


29,88 


30,25 


0,115 


March 


56 


33 


45.4 


59 


52.5 


56,8 


30,65 


29,83 


30,26 


0,122 


April 


58 


35 


44,0 


59.5 


51.5 


55.5 1 30.30 


29.38 


29,86 


».47o 


.May 


66 


47 


56,3 


66 


58 


60,9 


30,14 


29,50 


29,90 


2,898 


June 


86 


53 


60,5 


73r5 


60 


63,1 


30,3s 


29.49 


30.03 


0,708 


July 


73.5 


53 


6a, 2 


67 


61 


63,5 


30,20 


29,29 


29,84 


«,700 


Augad 


77 


51.5 


63.4 


7S 


6i,s 


65,* 


30,16 


29.64 


29.97 


1,991 


September 


68 


45 


56,6 


65 


58 


60,8 


30,42 


29,31 


30,00 


0,368 


Oaober 


64.5 


39 


52»4 


^3.5 


55 


59.5 


30,40 


39,62 


29,89 


1,108 


Movember 


53 


3* 


H,3 


59 


SO 


S5.4 


30,40 


39,02 


29,81 


2,512 


December 


5* . 


30 


♦0,9 


S8,5 


*8 


53.6 


30.38 


28,80 


29,88 


2,093 


Whole j 
year J 






50,9 






58.5 






29.98 


16,052 



IND OF FART I. OF VOL IXXXU 






I 




^ 9e ^ «^M« ^ Of ^ 3K * 30( ja 
^♦••y <)>»«iJ» ^•••F IkJIOiGk > 



PHILOSOPHICAL 



TRANSACTIONS. 



VTIL On the Rate of Traveiling^ as performed fy Camels ; and 
its Applicatioh^ as a Scale j to the Purpo/es of Geography. By 
James Rennell, Efy. KR. S^ 



Read March 17, 1791^ 

AMONGST the difcoveries and improvements of various 
kinds, that may be expe£ted from the very laudable^ and, 
as it concerns mankind in the grofs, no lefs humane and bene- 
volent inditutiou of AN association for promoting dis- 
coveries IN THE interior PARTS OF AFRICA, that of the 
geography of the Continent in queftion may be expedted to 
make the quickeft progrefs : fince, in every kind of diftant 
refearch, whether fuccefsful or otherwife, the aft of enquiry 
alone brings materials to the geographer. Fut, even with every 
Vol. LXXXI. T ordinary 



I JO Mr. RfiNKELL on the Rate of 

ordinary advantage, the geography of a continent muft oecef^ 
farily be flow in its progrefs towards maturity ; w^, therefore, 
can only expefk to witnefs its early infancy; and canAot, ieom 
a view of the prefent, allow ourfelves to predi£k what its 
future features may be. Let it be our care, however, to fofter 
it ; and contribute all within our power towards its improve- 
ment and perfeftion. 

In a cafe where there is fo little probability, even in a long 
courfe of time, of obtaining many fixed points by celeflial 
obfervations (though I hope that one at leaft will be attempted 
in the central part of Africa, in our time), it is fortunate that 
the mode of travelling happens to be fuch, as ferves to furnifh 
a remarkably equal fcale : the rate of the camel's movement 
appearing to be, beyond all others, the leaft variable ; whether 
we examine it by portions of days, or of hours. In the prefent 
ftate of things, the former mode alone canbeufed; becaufe 
few or none of the African travelers carry watches with them: 
but it may be hoped, that at no very diftant period, the time 
employed on the road may be obtained with fuch a degree of 
exadnefs, as to furnifh the geographer with materials of a far 
better kind, than any of thdfe, formed on computation, that 
have hitherto been exhibited. 

Thefe remarks occurred on the refult of an examination, 
which (though for a diiEFerent purpbfe) I lately made into the 
rate of the earners mdVement on the Arabian defeft, between 
Aleppo, Bagdad, andBuflbrah: for it appeared tome, that if 
the African caravans are compofed of the fame kind of camels, 
and are governed in their motions and oeconomy by the fame 
circumftances, asthofe tfrhich crofs the Arabian deferts; there 
is no fcale, of the computed kind, that can be more applicable 
to the Afri(^an geography, than that formed on the camel's rate 

of 



€f travelltpg* I (hall therefore detail the examples from 
whence I have drawn the proportions for the hours and days 
journey of the camel^ un^er the two different degrees of bur* 
then, which conftitute what is commonly denominated the 
LIGHT, and the heavy caravan. 

The routes which furnifli the above examples are determined 
in their horizontal, or direft diftance, by the refpe£live pofi- 
tions of Aleppo, Bagdad, and Bussorah : all of which 
have their latitudes and longitudes fixed by celeftial obferva- 
tions *• Thefe routes are five in number : and although fome 
t)f the journals that defcribe . them, contain lefs information 
than t)thers, yet all of them have the time given with a fuifi* 
cient degree of predfion, to enable me to found a general rule 
on. Three of thefe routes lead acrofs the orbat desert, or 
that between Aleppo and Builbrah ; the other two are acrofs 
the LITTLE DESERT^ Of that between Alej^ and Bagdad. 

The firil of the Great Defert routes was traced by a Mr. Car* 
MICHAEL in 1 75 1. The manufcript copy of his Journal was 
ob^gingly communicated by my friendDr. PatrickRussell;; 
and it manifefts a great degree of ingenuiCy and perfeverancd 
ia this way. The Author declares, that he was determined to 
keep a regifler of the couries by a compafs^ and to compute^ 
comparatively, if not abfolutely, the intermediate diftance on 
each courfe ; by comiting the fleps or paces of the camel on 
which he rode, during a certain interval of time ; and after- 
wards meafuring a number of them on the ground. The 
particulars of this operation (hall be given hereafter; >nd 

♦ Aleppo, 10 Coini. dcs Tctops, lat* 36° 11', long. 37*^9% reckoned from 
Greenwich. 

Bagdad, by M. Beauchamp, lat. 33° aa', long. 44'' 21', Greenwich. 
•Buflbrah, by Capt. Ritchie, \\U jp" 30', long* 47° 33', Greenwich. 

T a although 



132 ^ Mr. REtf VEIL on tie Rate of 

although Mr. Carmichael failed in the attempt to afcertaiithls 
road didance by this method, yet his prbcefs has furniflied others 
\(^ith the means of afcertaining the whole diflanceiu theaggre-* 
gate, and of proportioning the parts throughout. For, as the dire& 
didance is given by the celef^ial obfervations, and a complete 
traverfe table by the journal, the data are perfeft. And when 
the reader is informed that Mr. Carmichabl's whole line of 
bearing, by compafs^ between Aleppo and Bufibrah, nearly 720 
Britifh miles, coincided with the bearing line given by the 
celeftial obfervations \ by which it appears that the error could 
amount only to the mean quantity of the variation throughout, 
which might have been from (ix to feveh degrees at that time 
(1751); he will give Mr. Carmichael credit for much 
general accuracy. And it is not improbable, that even* a confi- 
derable portion of the above error may have arifen from: the 
imperfe£lion of his inftrument •. 

The fecond journal was kept by Colonel Capper, in 1778, 
and was publilhed feveral years ago ; and the third, which 
contains little more than the time in detail, was communicated 
by my friend Mr. Hunter, who croflcd the defert in ^^f^^• 

The time given between Aleppo and Buflbrah, by thefe 
journals refpedively, is as follows : 

By Mr. Carmichael • 322 hours. 
Colonel Capper • 310 

Mr. Hunter . 299I 

* I find, by Mf.Dkummond^s chart of the road between Aleppo and Antioch 
(1747)9 that the variation was then about 6 degrees wefierly. This is proved by 
comparing his magnetic bearing line between thofe places, with that given by the 
difference of latitude la the head of the Gulf of Ferfiay the variatioo^ was 
7 degrees in 1785. 

But 



Travellings as performed by Camels. i.^^ 

But to (hew that this difference arofe chiefly from the varia* 
tions in the route acrofs the chaldean desert (between 
Mesjid All and Buflbrah ; fee the annexed fketch, Tab. III.), I 
ihall proceed, firft, to explain that part of the fubjeA ; and 
afterwards to exhibit the particulars in proof. 

Mesjid Ali (or Ali*s Mofque) is fituated at about two thirds 
of the diftance, and as nearly as poflible in the line of direction, 
between Aleppo and Buflbrah ; and is a fort of land«mark to 
the caravans wiiich pafs the common boundary of the Arabian 
and Chaldean deferts. Its geographical polition is deduced 
from bearings and latitudes taken by M. Nibbuhr and others : 
and therefore, as far as general geography is concerned, it 
may almofl be regarded as a fixed point. Not that the truth of 
its poiition will in any fhape affedl the prefent head of enquiry ; ^ 
which is entirely direfted towards a comparifon of the fpaces 
of time, employed between certain points of the route, by each 
traveller^ refpeftively. 

Now, that portion of the Defert route between Mesjid Ali 
and BufTorahy being fubje£t to great variation in the track, as 
appears by the journals of different travellers ; whilfl the much 
larger portion of it, between Mesjid Ali and Aleppo, is very 
nearly the fame at all times ; it is very clear, that this latter 
portion furnifhes the properefl ground on which, to form the 
comparifon : and the particulars are as follow :. 



Aleppo 



«3+ 



Mr. RfiNKfeLL on fhe Rait tf 





Carmi- 

CHABL. 


Capper. 


HuKTEfc. 




Aleppo to Hagla 


H. M. 
" S 


H. M. 
11 34 


H. M. 
10 


HagU. 


Hagla to Ain il Koom 

Ain il Koom to Uklet Hauran 


37 30 
80 lO 


41 4 
7841 


35 
81 30 


M Taiba. 

CO Uklet Hauran. 


Hagla to Uklct Hauran 
Uklet Hauran to Al Kadder 


117 40 
S3 50 


119 45 
54 45 


116 30 
51 30 




Hagla to Al Kadder 
Al Kadder to Rackama, op- 1 
polite Mesjid Ali . J 


171 30 
21 45 


174 30 
19 50 


168 
19 30 




Hagla to Rackaraa « 


193 15 


194 20 


187 30. 




Aleppo to Rackama 


204 so 


205 44 


197 30 





Oil the Little Defert I have two e)camples of time, from Mr% 
Irwin in 17S1, and Mr. Holford in 1780; both of whom 
kept regular journals. 



Aleppo to Ain il Koom. . • • 
Ain il Koom to Annah on the Euphrates 




Hoxj^ftD. 



XI* AS* 

80 15 



Aleppo to AiMiah 



l%b ^ 



It appears by the journals, that iMr. feWiK deviated frotn 
the ufual track in the firft part of his rotite; atfd that Mr. 
HoLFORD did the like in the latter part of his ; each to avoid 
an enemy : fo that it may be prefumed, that the deviations 
nearly balanced each other (fee the Iketch). 

Between Annah and Bagdad, thefe gentlemen made part of 

their journey in the caravan of loaded camels, and partly with 

Ught camels (that is, without any other load than the rider)# 

Mr. Irwin employed 6ii hours: but the laft 15 hours, on 

2 light 



Travellmgf as fefformedhy Camels. ijy 

light canaelsy were at an accelerated rate of haff a mile per 
hour, or one fifth part, above the ordinary rate ; according to 
his idea, which I have no doubt was a very juft one : and this 
accelerated rate (hbirld add 3 hours to the 15, to reduce It to 
caravan time ; making 65! hours inftead of 62 f. Mr. Hol- 
ford's journey, by the fame ratioj muft be reckoned at 68 :: 
but as this part of the two journles is obvioufly too inaccurate 
to draw any concluiions from, in the way of comparifon, I 
ihall only make ufe of Mr. Irwin's time (to which no folid 
objeSion can be urged) when I calculate the rate of the camel's 
travelling. 

We have now feen, that on a journey of about 200 hours, 
between Aleppo and Mesjid AU, two accounts differ only i hour 
24 minutes ; and a third differs from th& mean of the other 
two fevcn hours and an half. And we may obferve, that if the 
ftage from Aleppo to Hagla be taken out of the queftion, the 
number of Mr. Hunter's hours would be nearer on an equa- 
lity with the others by about an hour and a quarter (fee 
p. I34*)« The reafon of the difierent reports of the diftance 
between Aleppo and Hagla, appears to be, that travellers com- 
monly join the caravans either at Hagla or on the road to it ; 
and they, travellbg by a quicker conveyance than camels 
afibrd, and then adjufting the time to the caravan rate, make 
different eftimates of the diftance.. Or there may be fome 
other caufc which has not been explained* Four diffcrenr 
peribns give the time as follows : 

a M. H. M. 

Carmichael II 5 Capper ii 24 

Hunter id o Holford 9 12 

So that the proper point of outfet in making the comparifon, 

is 



1136 Mr. Rennfxl on tie Rate of 

is Hagla. And, reckoning from thence, we have in the £rft 
table (p. 134.) the numbers 193 J> I94ff and 187!, for the 
time between Hagla and Mesjid Ali, in the three journies 
Tefpefttvely : and the fame tableaffbrds alfo the following com-> 
parifons between difierent places on the route : 

In one inftance, 804., and ySi ; 

In a fecond, • Hjii 119I9 andli6|; 

In a third, • .53 J, 54*, and 51!; 

And in a fourth, lyii^ I74i» and 168. 
Again, between Aleppo and Annah on the Euphrates, the 
numbers in the fecond table (land thus : 

128, and 1261. 
I thuik I need not produce any niore examples to prove the 
equal rate of motion of a camel that is in any degree loaded; or 
rather of a number c^ camels together, where the rate will be 
determined by the Jlow-going ones : and whatfoever rate, in a&ual 
diflance, may be deduced from thefe examples, muft be applied to 
loaded camels travelling in a body together, and not to light 
camels, or thofe chofen for fpeed, whofe rate appears to be at 
leaft ^th greater* By a light camel is meant one that has 
only a man^ or a very fmall quantity of baggage, on it; 
whereas a camel's load is 500 to 600 pounds ; and camels fo 
loaded, form what is termed the heavy caravan* Light cara- 
van, on the contrary, is applied to camels under a moderate 
load, or perhaps little more than half loaded* And with 
refpeft to camels, either moderately or fully haded^ I can per- 
^eive no difference in their hourly rate of motion : the difier- 
•cnce alone appears in the length of their day*s journey ; as we 
fliall perceive hereafter. A camel, it is faid, will not permit 
himfelf to be over-laden ; and this may be the reaibu why the 
load docs not affeA his rate of motion. 

It 



Travellings as performed iy Camels. i^f 

It appears^ that the dired diftance between Aleppo and 
Buflbrahy is 621 geographic miles, or 720 Britiih» nearly. And 
Mr. Carmichasl*s route, traced by a compafs through all 
its principal bendings, and calculated trigonometricallyt gives 
688 geographic miles, or of Britilh 797* It follows then, of 
courfe, that as the fame gentleman was 322 hours on the road,- 
the mean hourly rate of the camel's nootlon, was 2,475 Britifii 
miles. Colonel Capper's route, though eafily traced on the 
map, is not corre£l enough in its particulars, to ierve as an 
authority equal to Mr. Carmicuael'sj and the like may be 
iaid of Mr, Hunter's : but they muft both, be allowed to coi> 
roborate Mr. Carmichael's in a general way; for as nearly 
as Colonel Capper's route can be traged, over the Chalpban^ 
Defert (and, as we have before obferved, the track is nearly 
the fame at all times, in all other parts of the Defert) the 
hourly rate of his camels was 2,51 j^^r hour; and that of Mr, 
Hunter's 2,585. 

We come now to the little desert route. It has been 
noticed, that Mr. Irwin employed 128 hours on his journey 
from Aleppo to Annah ; and 65 i more (allowing for his acce- 
lerated rate 3 hours, fee p. 135*) between Annah and Bagdad; 
altogether 193I hours between Aleppo and Bagdad. The dire£k 
didance between thofe places is 393 geographic miles ; and by 
the route traced by Mr. Irwin, the road diflance comes out 
about 414I, or Briti(h miles 480*. And this number, 
divided by 193!, gives 2,48 per hour for the camel's rate ; or 

* Not that the diftance between thofe places is fo much as 480 miles by the 
dired road : it is probably Icfs than 470. But Mr. Irwin's party took a cir- 
cuitous courfe to the fouthward, between Aleppo and Ain il Room, to avoid an 
enemy that lay in the way. He efiinoated his diftance at 493 miles. 

Vol. LXXXI. U wthin 



138 Mr. Hbknbll on the Rate if 

witiiin a very fmall ivz&xon of Mr. Carmichasl's rate ; his 

being, as we have juft feen, 2,475. 

I think I may venture to reft the calculation of the loaded 
camel's mean hourly rate of travelling, on the experiments of 
Mr. Garmichasl and of Mr. Irwin; both of whom appear 
to have taken much pains with the detail of their journics*; 
and then it will ftand as under ; 

Mr. Carmichael on 322 hours a,475|Mean 2,478 Bri- 

Mr. Irwin on 193! . . 2,48 J tifli miles. 

We have mentioned above, the refult of Colonel Capper's 
and of Mr. Hunter's time, which gave a rate fo very near to 
Carmichasl's and Irwin's : and it may not be amifs to add 
to thefe, the refult of Mr. Hot ford's; as well as theeftimates 
of the camel's rate, formed by feven different perfons. All 
thefe I have placed in one point of view, in the following table. 







i 














Carmi- 
chael/ 


UWIK. 


Capper. 


Hunter. 


HOL- 
FOED. 


Plaistrd. 


Anony- 
mous. 


Eftimated. rates 


Brit. mi. 
2,29 


2,S$ 


^as 


2.33 


2.24 


2.3 


2,S 


Experiments 


2,475 


2,48 


2.51 


2,585 


2,5 







. Mc^n of the feven eftimates, ^^35* 

Mean of the five experiments, 2,51. 

Mean of Carmichakl's and Irwin*s, 2,478. 

♦ Mr. Irwin alfo took the bearings of his courfe by a compafs^ though notfo 
viuch in detail as Mr. Carmichael; bac Mr. Irwin not only remarked the 
time, but the particulai rate of travelling, on each day; which appeared to vary 
from 2 to 3 ^r hour, but was commonly ai > and the mean of all 2,55 Bricilh 
miles« 



Before 



Traveling, as pnfofmed iy Camels, 139 

Before I quit the fubjeft of the hourly rate, I (hall obferve, 
that the road diftances in Mr. Carmichael^s traverfe table 
are often thrown together in lines of very confiderable length, 
fuch as ao miles and upwards; and very commonly in lines of 
5, 6, and 7, and yet are all confidered as flraight lines* By 
this mode, it is probable, that many fmall inflexions palTed 
iinnoticed : and therefore the rate taken from the refults of 
Garmicha£L*s and Irwin's obfervations, will be rather under 
the mark than otherwlfe ; but it is obvious, that no kind of 
rule can be found to corre<ft it by. It is certain, that fewer 
mflexions are likely to occur in the Defert routes, than in almbft 
any other ; not to mention that the long lines of diftance hap- 
pen chiefly in the open, level part of the route. The road 
diftaoce exceeds the dircQ, diftance, by one-fourteenth part of the 
latter only, between Aleppo and Mesjid Ali ; amounting to a 
fraction of ,168 Britifli mile on each hour; or in the propor- 
tion of 7i miles on each hundred of direffc diftance. This, I 
confefs, is much lefs than I could poflibly have fuppofed ; and 
which nothing fhort of adual experiment could have induced 
me to believe. On the whole road between Aleppo and Buf^ 
forah, the proportion is nearly 1 1 on each hundred, on Carmi« 
chael's route : but his route over the Chaldean Defert was 
unufually circuitous; and cannot be admitted to have any 
weight, in the determination of this queftion. 

One would expcfl that the inflexions of which no account 
is taken by Mr. Carmichael, would amount to at leaft half as 
much as thoie which are taken notice of; and fuch addition 
would make the whole hourly rate Zy^6 inftead of 2,475. But 
this is merely a fuppdition ; and it is poflible, that the rate may 
not be higher than 2,52^ the mean of the four other cxperi- 

U 2 ments. 



140 Mr. RtiNNSLL on the Rate of 

ments. At all events, the error can be but fmall : and poili- 
bly, all circumflances taken into the cafe (and particularly 
this remarkable one, that of three perfons who attempted to 
afcertain the rate, by counting and meafuring the camefs foot- 
fteps, none reckoned it higher than 2|, and one went fo low 
as 2 1), I think the rate of two miles and an half per hour may- 
be ufed, as differing but a (hade from the general refult ; and 
as having the moft manageable fradtiou. 

Thus it appears to me, that the hourly rate of the camel 
may be applied as a very ufeful fcalc to the African geography ; 
whenfoever the ufe of watches (hall be adopted by the native 
travellers employed by the African association * ; and with 
iUll greater advantage, of courfe, if Europeans are employed. 
And if Mr. Car>iichael could defcribe the general bearings 
on a line of more than 700 British miles, fo nearly as within 
6 or y degrees of the truth ; and that with a pocket compafs ; 
nothing more need be faid concerning the advantages that may 
be derived from the ufe of that valuable inflrument, aided by 
fuch a fcale as I have been defcribing. 

The mean length of the day's journey of the camel, varies 
according to the degree in which it is loaded : andin this'J)arti- 
cular it is that the (late of the camel, as to its burthen, ope- 
rates pn its progrefs. It is neceflary to obferve, that whatfo- 
ever remarks I may offer, on the fubjedl of the camel's day*s 
journey, are meant to be applied only to the mean rate on jour-»» 
nies of confiderable length ; fince any other kind of experiment 
would be of no ufe in geography : I fliall therefore confideronly 
the progrefs of the lioht and heavy caravans, in which 

* la the Memoirs of Abdul Kurrim, a Caflimerian of diftia^ion, he informs 
uiy that he kept ah account of the time, on the road between Bagdad and Mecca^ 
by meaas.of an European watch^ 10 the year 1740.^ 

the 



Travelling f as performed by Camels 141 

the camels are left to purfue their journey quietly and at lei- 
fure ; and with the regularity of a machine : and not that of 
the LIGHT CAMELS, which are not only freed from incum- 
brance^ but are alfo urged on. 

I have two examples of the heavy kind, and three of the 
light kind, where the time has been regularly kept : befides a 
third example of the heavy kind, where the neceffary regularity 
is wanting, but yet containing within itfelf, evidence fuffi- 
ciently ftrong to corroborate the other two. 

The HEAVY caravans were thofe of Mr.CAEMiCHAEL 
and M. Holford; the firft of 1000 camels, of which 
600 were loaded, went, on a journey of 45 days, at a H. M* 
mean, each day, • • • • 7 10 

The fecond, with 50 loaded camels, on a journey of . 
15 days • • • • • 

Mean of the two. 
The third, Teixeira, with 130 loaded camels, on a 
journey of 21 days, about . . 

Mean of all, per day. 

The LIGHT caravans were, 

H. M. 

Meif. Irwin, n^ ' r 21 days, 9 12 

C*P,E., If'om 80,0, oof ^ - 838 

HVNTER, J "™''' L34 — 8 45 

Mean of the three 8 52 

Here then the mean of the heavy caravan day is under feven 
hours and an half; and that of the light caravan between 
eight and three quarters, and nine hours. 

Some 



7 40 


7 as 


7 30 


7 27 



141 Mr. Rennell on the Rate of 

Some of the ordinary watering places on the Defert^ being 
from 3 to '5 days journey afunder, it may be fuppofed, that 
the length of the intermediate journies, would be determiaed 
by the known and approved ftandard of a proper day*s walk 
for a camel : for as they often arrive at the watering-place 
early in the day, it appears, that the caravan chiefs, do not, by 
any means, divide the ground between fuch watering places, 
into equal portions for marches. This being the cafe, one may 
exped to arrive at the knowledge of what is at leaft intended 
for a proper day's journey for a camel, under the circumftauces 
of the cafe : and indeed the refult is fuch as to prove what I 
have before advanced, refpefting the length of the mean journies 
of both kinds. For having feleded from the five above^ 
mentioned journals, the length of the j/^^m//^ optional journies 
in each ; it appears, that the heavy caravans went 7 h. 5 1 m. 
On a mean of 24 fuch days : and the light caravans 9 h. 8 tn, 
on a mean of 38 days. In both of which cafes, as might 
have been expeded, the length of the mean optional day, i^ 
fomewhat longer than that of the whole journey; in which 
there is a wider field for delays and accidents. The compa- 
rifon is as follows : 



Heavy caravan. 


Light caravaa. 


Mean daily rate of the 
whole journey . . 


H. M. 
7 27 


Diftaoce in Britifh 
miles. 


H. M. 
8 52 


Diflance in Hritilh 
. miles. 


at 2| 
per howr, 

18,64 


at 2,56 
I9,o0 


at2i 
perhouT. 

22,17 


at 2,56. 

22,7 


Of optional days . • 


7 51.. 


>9>6a 


20,I 


9, 8 


22,8 


23.38 



Thus 



Tnwelling^ as performed iy Camels, i^^ 

' Thus the mean daily rate of the heavy caravan, appears to be 
18,64 Brltifh miles, reckoning two miles and an half for each 
hour; and 19,06 if taken at 2,56 : and the mean rate of th? 
light caravan 22,17 miles, at 2| ; 22,7 at 2,56. 

In order to apply this fcale with effeft, to the African geo- 
graphy, it is neceflary to ftate the number of days that the 
caravans ufually halt on the road j for as yet I have only confi- 
dered their rate of motion : but it is evident, that if the length 
of the journey in the grofs, is given, the requilite information 
will not be obtained, without a previous knowledge of the time 
loft by neceflary, or unavoidable halts on the road. My enquiries 
have furniflied me with an account of 13 halts, to 149 days of 
travelling; or, which is the fame thing, 13 halts out of 162 
days, reckoned from the time of departure, to the time of the 
arrival of the caravans at the place of deftination : that is, i 
halt to I2| travelling days. This, of courfe, muft be de- 
ducted from the aggregate of the diftance : or, fhould it be 
averaged on each day, the heavy caravan day muft be reckoned 
at 17,14 miles inftead of 18,64 J ^^^ ^^^^ of the light caravan 
20,4, inftead of 22,17; when the hourly rate is taken at two 
miles and an half. 

It alfo remains to be ftated, frorri the proportion that the 
road diftance bore to the direft diftance, by the trace of Mr. 
Carmichael's route; what length in diredl diftance, and 
in geographic miles, may be allowed for eacih day, for the 
heavy caravan, on fimilar lengths of journey, and over fimilar 
trads of country. It appears then, that on the 28 days be- 
tween Aleppo and Rackama (oppofite Mesjid Ali) the mean 
length of the day*8 journey, in direfl: diftance, is about 15I 
geographic miles : and on the whole 45 days between Aleppo 
and Buflorah, 13,8 fuch miles. But this is without any allow- 
I atice 



144 ^^* Rbnnell on tie Rate of 

ance for halts ; which, as has been obfe.rved before, require a 
deduction of 8 parts in loo, to be made from the grofs amount; 
of^ the whole journey, when applied to the purpofes of geo- 
graphy. 

1 have already taken notice, that Mr. Carmichael counted 
the earners fteps, in order to afcertain a fcale of diftance ; an(^ 
I {hall now give the refult of his obfervations, as well as of 
Mr. Holford's, who alfo counted the fteps, and meafured the 
length of a number of them on the ground. Mr. Hunter's 
experiment was on too fmall a fcale to ground a calculation on. 
It is certain, that thefe reports of the number of fteps during 
jcertain portions of time, and the meafurement of a certain num- 
ber of thofe fteps on the ground, furnifti a refult that does not 
agree with the experiments on the great fcale ; fuch as we have 
juft related, and which appear to be fufceptible of greater accu- 
racy than thofe made in detail. But it will, neverthelefs, be 
proper to give the refults, and to make fome remarks on 
them ; if be only to prevent any perfon in future from found- 
ing a calculation on them. 

Mr. Carmichael counted the double fteps, or rather the 
return of the fame foot, of a camel on which he rode, for an 
hour together, on 20 different days ; at times when, from the 
nature of the ground, he thought the greateft variation took 
place, in the rate of motion. He found the greateft number of 
fteps to be 2420, the leaft 2086 ; and the mean of the whole 
20 hours, was 2200. Mr. Holford reckoned the greateft: 
2240, leaft 2060; mean 2150. They both report the double 
ftep to be 5 feet and an half. The refult of the former account 
is 2,29 Britifti miles per hour; of the latter 2,24; and each 
allowed his diftance accordingly, in his journal : though nothing 
is more certain than that their computed diftances fall very 

fliort 



[ I 



-./ 










-y 



A 



Travellings as performed iy Camels. 145 

Ihort of the truth. Mr. Carmichael, for inftance, reckons 
the diftance from Aleppo to Buflbrah, by the road, at 720 
BritUh mtles^ although the direft diftance itfclf fcarcely falls 
fliort of it. And Mr. Holford's road diftance alfo falls very 
(hort. Even Mr. Carmichael's higheft number of paces, 
would exceed the mean rate given by the experiment at large, 
by zjixtieth part only. 

As thefe gentlemen's experiments differ only 50 fteps, In 
the mean number, during the hour (one being 2200, the 
other 2150), that is, a 44th part, the error muft be looked 
for elfewhere ; and it probably originated in their meafuring 
too fmall a number of fteps on the ground to found their cal- 
culation on. 

The reafon of this great variation in the number of paces, 
in a given time, is the plenty or fcarcity of the Defert ftirubs, 
on which the camels feed, as they go on ; and thus fuch expe« 
ments become almoft ufelefs, unlefs the quality of the Defert 
was defcribed in every part. As the hourly rate of Mr. Car- 
michael, coincides with that of Mr. Irwin, within a very 
fmall fradion, although the one travelled in November and 
December, the other in March and April ; it appears, that the 
feafons have little or no efieA in this particular: and it is 
therefore highly probable, that the flirubs may fiourifli in fome 
parts of the Defert, and be dried up in others, at one and the 
fame feafbn. 



Vol. LXXXI, 



[ »46 ] 



IX. On Infinite Series. By Edward Waring, M. D, F. R. S. Lwa^ 

£an Prefefor of Mathematics in the Univerpy pf Cambridge* 



Read March 24, 1 79 1 . 

I. Ti ijERCATOR firft publi(hed the contiuation of the 
X ▼ JL common method of divifion to an infinite ferles of 
terms proceding according to the dimenfions of a variable quan- 
tity ; Newton did the lame for the common method of ex* 
tradion of roots. Dr. Barrow before applied the fame princi* 
pies in fome eafy examples to find the afymptotcs of curves. 

2. The methods of divifion and extraction of roots werc^ 
long before taught; but the continuation of them in tn^ 

J^niium would have been ufelefs, as the areae of curves, whofe 

« 
ordinates are ^a?" (where x denotes the abfcifs, and tf, n, and tn 
invariable quantities) had not been difcovcrcd many years before 
the time of Mercator*s Publication, and eonfcquently it 
would have been of little ufe to transform an ordinate or fkixiony 
whofe area or fluent is unknown, into another ferrm> of whkEi 
the area, &c. is equally unknown. 

3. Sir Isaac Newton extended the rule for raifing a bino- 
mial (to any affirmative powefr) to negative powers, the ex* 
tradion of roots and fradional indexes, by applying the law' 
of the feries for affirmative powers to them, and continuing it 
in infinitum. M. db Moivre extraded the root, &c. of a 
multinomial by a feries of a iiffiilar nature; but thefe methods 

wiU 



Dn Waring on^ fee 14^ 

will only apply in the moft fimplc cafes, when not more than 
one root is to be eXtrafted. In ev6ry complicate cafe f'vi^. 
the extradion of roots of quantities -which involve the roots of 
compound quantities) of irrational quantities, recourfe muft 
be had to the old methods of multiplication, divifiou, and 
extraction of roots. 

4. If a root of a complicate irrational quantity be required 
by a feries proceeding according to the dimenfions of * ; firft 
reduce all the irrational quantities contained under the root by 
multiplication, diviiion, and extraction of roots into feriefes 
proceeding according to the dimeniions of ;r, fo that the terms 
of the lead dimenfions be conftituted firft, if an afcending 
feries be required, and fo on ; and the contrary, if a defcend- 
ing ; then add the feveral fums together, and extract: the root 
of the refulting fum by a feries which proceeds according to 
the dimenfions of at, and it will be the root required. 

Ex. Let the value of the quantity^ (jc^^ + a+i + cxy, 

Z^ (d+ex + ^(f+gx^))+^(6 + kx'y) be required by an af- 
cfeading feries ; firft^ cxtrad the innermoft root y/(/+^**)*»,j 

jT* + ^ - &c. which add to the quantity i/+ ex contained un* 

der the fame root (/»), and place the terms of the fum 
According to the dimenfions of x, and it becomes (d+f^)+^x + 

i^-Ac. pf whidf cxtraa the (m) root, and there refult3 



{d^fif+lxd+Ji- rKfx+lxlZZxii+f^- ^e^ 



m '^ w 2OT 



^•+. 



2cc» multiply thU feries into b+cXf and thence is derived 

X 2 bx 



148. Dr. Waring ^« 

A? + &c. ss P ; extrad the root 



t— HI 






+ cx ^+y*- ^ 

v/A+i6x* = A4 + ^ + &c. = Q; add the three quantities P, Q, 

an4 X-* + ^ contained under the fame root v^ together, and the 
Xeries refulting, whofe terms are conflituted according to the 



dimenfions of x^ will be x^^+ (j + 3x^+/i"+ bi^ A) +, 
(l6xii +fi~^xe+cxd'\-fi''=B)x + Scc,; of which cx- 

traft the cube root v^, and it will be x^^ + iAx^+^Bx^ + &c. 
the root required. 

5. The principal ufe of reducing quantities into feries pro- 
ceeding according to the dimenfions of the Variable quantity is 
as before mentioned for finding the area of a curve from its 
ordinate ; or, which correfponds, the integral from its nafcent 
or evanefcent increment ; but the feriefes deduced (hould con- 
verge, otherwife from them cannot be found the area or integral. 
In the Meditationes Analytical a method was firft publiQied 
of finding when thele feries will converge and when not, e. g. 
the feries a + bx + cx* + iix' + &c. =z f {A + Bx + Cx* + Dx^ + 
6cc.Y X x-^^P will converge when (x) either affirmative or ne- 
gative is lefs than the leaft root (as) of the equation A + B^ + 
C;r* + Djc* + &c.=o, if the roots are poflible. A fimilar rule is 
given when fome of the roots are impoffible. The feries will di- 
verge when X is greater than «, and the cafes are given in which 
it will converge when xizcc. The feries defcending according to 
the dimenfions of ^;i; will converge when ;i? is greater than the 
greateft root of the equation, &c» Thefe principles are fur- 
2 ther 



Infinite Series^ 14^ 

ther applied in the fame Book to complicate irrational alge- 
braical functions of x^ &c. 

Hence moft commonly the feries for the area contained be- 
tween two ordinates, or integral between two different incre- 
ments deduced by the common method will diverge ; on which 
account, in the fame Book, is given a method by interpolation 
of findiDg the area or integral contained between any two dif- 
ferent values oix by converging feries, if the area, &c. is finite. 

6. To find whether a given value { + d) is lefs than the 
leaft affirmative or negative root (x) of a given algebraical 
equation A + Bx + C**+DAf' + &c.= o, if all its roots are 
poffible ; transform the equation into another, whofe root % is 

the reciprocal of the root a:=: - of the given equation, and for 

% in the refulting equation write refpeftively v-^.a and v^ai 
and if from the former fubftitution all the terms become ne- 
gative or afErmative, and from the latter they become alter- 
nately negative and affirmative, then will a be lefs than 
the lead root of the given equation. If in the fame manner, in 
the given equation for x be fubflituted v + ^ and v^a^ and 
the terms refult as before, then will {a) be greater than the 
greatefl root affirmative, or negative of the given equation. 

7. When the integral of an algebraical quantity, whofe in- 
crements are finite, is required ; firft, by the method given in 
Medit. Analyt. invefligate the integral in finite terms, if it can be 
cxprefJed by them ; but if not, reduce it into infinite feriefes of 
which the integral of each of the terms can be found, and alio 
the feriefes for finding the integral contained between the two 
different given values of the variable quantity may converge. 

Seriefes of this kind have been given in the Medic. Analyt. 
and innumerable of a like kind may be added for finding 

integrals 



t^ Dr. Waring on 

integrals by converging fcrififes cither afcending x)i d^fcending, 

of which the given increoients are either finite or evanefcetit. 

7. 2. It may be obfervfed^ that generally the particular caf^ of 
which the increments are nafcent or evanefcent may be dcduceti 
from the general^ in which the increments are finite j and con- 
fequently in rtaany cafes the general Will, mutatis mutmdii^ 
correfpond to the particular; e.g. 1. the integral cannot be 
expl^ffed in finite algebraical terms, when any fador in the 
denominator of the incretaetit has not a fucceffive correfpon- 
detit one ; which is analogotiis to the cafe of the fimpl^ divilbr 
in the denominator bf a fluxion publifhed itl the Quadratune of 
Curves. 2. Nor can it be expreflfed by the above-mentioned 
terms, when the dimenfions of the variable quantity in the 
denominator exceed its dimenfions in the numerator by unity, 
which correfponds to a fimilar cafe in fluxions firft given in 
Aiedit. Analyt. To thefe may feveral others be added. 

8. Let the fluent of the fluxion (A + Bi?- + Ci" + &c.)* )(: 
s^-'x = ax^ + bx'^'^" + cx^+^'''+' 5cc. = (A + Ba;* + Cx'" + &c.y+' x 
vex' + fix^-^" + yx^-^^" 4- 6cc. = ^V + ^V-^ + cV-"+ &c. -^ 
( A + Bjt- + Cx^' + &c.)«+' X « ^'' + iS V-"+y V-»" + &c. 

I .If the infinite afcending feries^x* + iSx^+" +7*^+"+ &c. con- 
verges, then will the lerics tf;t^ + ^xH-« + c;t^*''+&c. converge, 
and nearly in the fame ratio ; and vice verfdf if the former 
diverges, the latter will alfo diverge. In the fame manner if 
the infinite defcending feries aV+iQ'^'''"^ + yV""**+&c. con- 
verges, then will the feries ii V + ^V""" + ^V""^ + &c. con- 
verge ; and if the former diverges, then will the latter alfo 
diverge ; and in all the cafes nearly in the fame ratio, except 
only when their convergency is the leaft. 

7 a; If 



Infiniti Seri€i^ i^x 

2. If the feries ^lJf^^t&lf•+■-^«^+•■ + &c* Converges, than will. 
the feries tfV + ^V-^ + cV-*« + &c. diverge, unlefs iu cafes of 
the floweft couvergency, where a?«s =i=v \/ri=i, and all the 
roots of the given equation are of the formula dtiV \/-±l j • 

when x^dtiV \/=^i, the fucceflive terms of the infinite feries 
deduced from algebraical quantities by the preceding method 
will ultimately, that is^ at an infinite diflance come more near 
to a ratio of equality with each other than any affignablc^ 
difference. 

3. If the fluxion be (A+Ri;"+C;c*» . . • • ^^ ^^-^'^i then 
will X = wr/r + d, andA^ = fl-r/r. 

Many more propofitions concerning infinite feries and their 
Convergency are given in the Medit. Analyt. 

4. Let the fluxion be /i + ^a^" x ^k^ of which find the fluent 
in a ieries afc^iding according to the dimenfions of .r, and ic 

will b. --x^-v (^+;^x i ^+« . j;j==i- « 5^ 



2 















•IWIf 



+ A+ 1 . w«+A+ 1 —nk* 



firA 



152 Dr. Waring on 

firft feries, which afcends according to the dimeniions of x% 

terminates, when ^^i-ii is a whole negative number; the 
fecond, which defcends according to the dimeniions of 
the fame quantity a:*, terminates when -^ is a whole 
affirmative number. The fluent will terminate both ways 
^hen -^ is a whole affirmative and m a negative num- 

ber greater than — ^. 

5. When ;» is a whole number or =0, the fluent / a + Ax' x^x 

can always be found in finite terms of jc, or in the above- 
mentioned finite terms, together, with the log. of jc; 

which appears from reducing a + i:xf into limple terms 

a* + ma"^^ ix' + m . ^^ tf«-* ^V» + &c., and multiplying them 

mto x^Xf and finding the fluents of the refulting fluxions : but 
theTeries found by the preceding method will not always ter- 
minate when m is a whole number, and the feries findable as 
above mentioned ; when properly corrcfted, it may be ren- 
dered findable, or, which means the fame thmg, the feries 
may be made to terminate. 

6. When the feries which exprefles the fluent of a fluxion 
terminates, we may begin either from one end of the feries, 
or the other; for example, in finding the fluent of the fluxion 

a + hx' xx^x, either afTume the feries a + ix^ x (ax*+' + 

^;tf*+«+i4.y;tr*+*''+»+&c,)or the feries a+ix^'^^ (A + B;c^ + 
Cx*"-h&c.); the former, as is before mentioned, terminates 

when 



tnfimte Strhs. 15^ 

when ^^^^^^ is a whole negative number ; the latter when — 

13 a whole affirmative number. 

In lifce manner affumc for a defccnding feries (^x*+ii)*+' ^ 
(«V+'"' + /3V+'-*- + 7.V+^-3« + &c.), or (^;c''+ i?)«+» x 
(AAr^^"+B;c-^'' + Cx-^3- + &c.); the former will termi- 
nate when — is a whole affirmative} the latter when 
If 

'"'''^^^^ is a whole negative number. 

It appears, therefore) that a feries will terminate equally 
by an afcending or defcending feries ; and the end of the one 
afcending feries is the beginning of its correfpondent deicend* 
log one. All tfaefe feri&fe% which Ao not terminate^ proceed 
on in infinitum ; one term in the former feries becomes infinitei 
when ^ + 1 +«^ « o ; and in the latter (L) when Vriwr 4- A =h 1 - 
^-=10 f z bebg a whole affirmative liuiUber* 

10. It has beet) obferved in the ^4edit• Analyt. that if fome 
quantities contained in the given irrational <oues are much lefs 
or greater than the reft^ it maj be preferable in the formeif 
cafe tp reduce them intoferiefes not proceeding accordmgtotht 
dimenlions of Xj but according to the dimenfions t>f thofe 
quantities ; and in the latter cafe according to the reciprocal 
dimenfions of them 1 and particularly fo if the fluent or inte- 
gral of the terms of the refulting feriefes can be found in £mxt 
terms, or by tables already calculated. 

From fimilar principles to thofe before given may. be found 
when the refulting feries will converge, and when not. 

This method will in many problems be ufeful, when the 
falue of a near approximate is known. 

Vol* LXXXI. Y Cfr 



154 -Dr. Waring on 

' Of this cafe I (hall fubjoin a few examples, of which fomc 

have been already publiflied in the Mcdir, Analyt. 

Ex. I . Let the fine and cofine of a given arc A be rcfpcc- 
tively s and c ; then will the fine and cofine of an arc A + e^ 
where e bears a very fmall ratio to A, be rcfpeftively 

j+ - ^—^—e* ^^^, + ' ;^* + &c.(the figns pro- 

cced by pairs alternately negative and affirmative) = j (i — 

~!-tx.* + '- ,-^c'-&c.) + c(l ^3 + '1 5 

I . 2r* I . 2 . 3 . 4r^ ' \r 1.2.3/^ l»2.S*^'S^ 

- &cO ; and ^ - - ^ r c^* H ^ — -, x se^ + &c. (the fifi;ns 

^ r I . 2r* 1.2. 3/^ ^ ^ 

iproceed as before by pairs alternately negative and affirmative) 

^ I . 2r* I . 2 . 3 . 4r* ^ r ^ 2 . 3r* ' * 

This feries can alfo eafily be derived from Newton's feries 
by plane trigonometry, and will converge much fwifter than 

the feries A — -—^ + - ■ ■ , 4 - &c. &c. if e bears a fmall 

1 . 2 . 3r* 2 . 3 • 4 • 5 ^* 

proportion to A» 

jEx. 2, Let ^ be a fmall quantity in proportion to /, and the 

given fluxKHi -,;;_— ==^.,^-p-p^ ^-^ X t - 

2/ X i2:l±Lzp!l' X ^' + &c. (P) ; the co-efficient of a term 

/ X e*" of this feries will be a fraction whofe numerator is 

r+^— W + I.-X2XfXr+/ +OT + 2. . — . 

a 23 

■ X2X*xr+/ — /» + a. — — • — — . — . — :- . — ^ — 
4 - - 5 2 3456 

X 



Infinite Series. t^g 

^x i^xt^x ?+7*""^ + &c., and denominator (r* + /*)*«+' ; and 
the co*efficicnt of a term /x^*"H-» will be a fraftion whofe 



w-f I m 



numeratoris 2/x (ot+i . r*+/* ->w+2.— 21 .2.xa*xf*)tl 
V a 3 ^ 

r^-/* -|./w4. 2 . — ^ . • — . X 2 r X r + /* -1 

•^ a 3 4 S 

&c.) and denominator (r* + /')**+* ; « being a whole number. 
The contintiation of thefe feriefes is loo evident to need enun* 
ciation, as muft generally be the cafe when the number of 
fndlors contained in the fucccflive terms continues the fame or 
increafes in arithmetical progrefSon ; and the factors them- 
felves increafe or diminiih in an arithmetical progreffion : the 
terms proceed alternately + and — by pairs. 

2. 2. Let the given fluxion be -rr^-r^ = -r^-TT'^^^+' 

-7Pri:7^--«c.^p^^p:p^.x^ (TmTF"^ ^ + *^' 

(Q) ; this feries becomes the fame as the preceding by fub(lL- 
tuting in it e' for / ; in this feries € is coniidered as variable^ 
in the preceding /• 

The fluent of the former feries (F) is /—^ — +— ^ -7 

■ ■ ^a ^ ^^- ^'^'Vl'^l!? ^ ^'- &c; ; the fluent of the latteir 

feries (Q) is the fame as of the former (P) except the firft 

term /—— : the co-efl[icieiit of the term i^ in the fluents will 

be the fame as the co-eflSicient of the term ^' in the feriefes 
(P) and (Q^) divided by A. 

This feries, when the tangent of a given arc is known, flndr 
the arc whofe tangent differs very little from the given tangent. 

II. Let t be incre^fedor dimiirifhed by a quantity e in 
^), where e bears a very fmall ratio to any root or value of / in 

Y 2 the 



,5^ Dr. Waring on 

the equations P=o or -i =0; and the refulting quautitf 

expanded into a fcric^ ar^-he + ce'-^di +&cc. proceeding accord*^ 
ing to the dtmenfions of e^ and this feries be multiplied re* 
fpedively into / and e^ and the fluents of the refulting 
fiuxioDS found } then will the former differ from the latter 

by A/ ; for the former will hej'ai + ae + ^. xtf* + — ^^x e^ 

+ flL— +&C., and the latter ae+^ ^• + -5fL. 4.&C. 

a . 3 . 4^^ «^ « • 3« 

z. In the fame manner, if more than one variable quan« 
titles X, y^ »9 Sec. are contained in (P), which are iucreafed 
by fmall increments or decrements ai» jS, y» &Cm may the 
increments or decrements of the quantity (P) be deduced from 
the incceoEientbl theorem* 

Ex. Let the quantity (P) be (a + hd^y, and a^ i, at, », and 
m be increafed by very fmall increments or, jQ, y^ S^ and i ;. 

then will (a+a+b+fix x+^'"^^y"^' zz{a+b^y+ (^+Av-)- x] 
log. a+S^Xi + mxia + ix^y^^ x («+/2Af + *(W x log. ar-^; 
«x'-»y)) + &c. 

The terms are to be ib placed, according to the dimenfions* 
of the incremcatft or decrements, that the greateft may firft 
occur. 

1 2. Let fbme compound quantities be increafed by any fmall 
quantities variable or invariable, but not the variable quantities 
contained in them ; then seduce the given quantity into a 
feries proceeding according ta the dimenfions of the final! 
quantities^ aad find the fluent, integral^ &c. a3 required. 



Ex. Let the given quantity be 



X X » » 






hifntte Series, t^y 






&c., where the quantity x" + <2* is increafed by a fmall quan- 

( — ;; — Ty+i - (^ + 1 - ^ + 3») X S) &c. The continuation of 
the feries is evident ; the letters P, Q, R,. S, ico. denote the 
fluents A^,, r "X., ^ /V^,, &c- 

From the length of the arc of an hyperbola or ellipfe given 
may be deduced by this feries the length of a correfpondent arc 
of an hyperbola or ellipfe, of which the equations expreffing 
the relation i>etween its abfcifTs and ordinates differ only by 
very fmall quantities from the equations exprefling the relation 
between the abfcifTae and ordinates of the former. 

13. The fame principles may be applied to the refblution of 
algebraical, fluxional, incremental, &c. equations. 

Ex. Let LmM, &c. (Tab. IV. fig. i.) be a given circle, 
whofe center is C and radius (r), and it be required to find an 
arc LM, (o that the area LSM defcribed round a given point S 
contained between the lines LS, SM, and the arc of the circle 
LM be equal to a given area (a). 

Find aa arc Lm» A nearly equal to the arc required LM, 
of which to radios i fubftitute s for the fine, and c for the co- 
fine, and write e for 0iM=:LM - 1m and b for SC; then will 

LMx-CAhT^x r^=fcSCx^ X fin.jarc;LM(^x (A+^- 

A + r 



1^9 Dr, Waring OT 

±±fL + —I±l^^ Sec.)) =^ xrdt* X ri + rS" x c x e=p^ 

ixfi xjr + -L^xc^' ^x// J^ .x€e' + 

2r \ 2 2 . 3r 5t . 3 . 4r* 2.3.4. 5/* 

&c.) = a ; in this equation for ^"^^^"^ fubftitute ^, and 

for r:d=^r write /, and the equation refulting will be e=ft 

h 2 h I b 4^._. b c 

— jr=p r X ce -zti i X jtf tt: X ce 

arr 1.2. 3*r' I • 2 . 3 . 4rr5 1.2.3.4. 5/r^ 

=;= fife. = TT. From it find ^ in terms proceeding ac- 
cording to the dimenfions.of ^r, and there refults ^«7r=t: 

I . 2tr 2 . 3rr* 

This method of refolving Kepler's and other problems of 
cutting a given area dcfcribed round a point, whether focus or. 
not, in a circle, when an approximate fufficiently near to the 
area to be found is given, will converge as fwift as any, known 
method. 

The refolution of this problem may be deduced fomcwhat 
different by the following methods. Let the letters ^, r, «, 
denote the fame quantities as before, and s be the fine of the arc 
L/w to radius i, and j + ^ the fine of the arc LM nearly = Lot ; 

then will — /" . ^_j rdb— xs + ozza; reduce the fluxion 
r into a ferics Pi + Q^i + RoV + Sc^'i + &c. and find 



the fluents of the fluxions Qi, Ri, Si, &c., which let be B, 
C, D, &c., there will refult the equation o-i — ^* + — d' + &c. a 
gaqp rs^y X — ^^^ whcre /=Br^=i=^r and A=arc Lm; find ^ 

in terms of a feries proceeding to the dimenfions of 9r, and 
fonfequently s + o the fine of the arc LM required* 

From 



Infinite Setters. j^^ 

From fimilar principles may be found the tangent of the 
arc required from the equation — /- — A-rr* =t= -Hi-iriLL. n « 

where the tangent/ to rad. i of the arc hm = A is given. Let the 
fluent of the fluxion ( ^—-5) = A + B/ + Ci* + D/' + &c. ; 

and '+''li -^ = A^ + BV + C'/^+ iy/' + &c., the equation 

Will become / + ;5^/^ + ;:5^^x /• + &c.--p5^;^ =^; 

from this equation inveftigate / = ^ + P7r' + Q7r' + &c., and 
thence / + / the tangent required. 

In like manner may be found the fecant, cofine, &c. of the 
arc required. 

14. The fame principles may be applied to cut an area de- 
fcribed round any given point in a given curve equal to an 
area «• 

Let X be the abfcifs and^ the ordinate of the given curve, and 
b the diftance of the beginning of the abfcifs from the given 
points, and let (A) be the area of the curve defcribed round the 
point S, when the abfcifs is x^ which differs very little from 
the given area («); to find the value a: + ^ of the abfcifs, when 
the area = a. 

htt y=zX a funftion of x^ and In X for x write x + e^ and 
reduce the refulting quantity (X^) into a feries X + Be + Ce^ + 
D^' + &c. proceeding according to the dimenfions of e; then 
will the zrczfyx=fXx + efBx + e^fCx+e'fDx + 8ic. = 
A + be + ke^ + h'-^-Scc.^ and confequently A + he+ie^ + le^+^ 
&c.dt(3=s=x+7) X ^ = A + be + ie^ + le^ + &cc. + l{Aztzx + e}x] 



(X + B^ + 0* + D^' + &c.) ^ A+ i(6^ x) xX-f^ih + it^:±zx X 

B 



i6o ^ Da Waring oh 

£cc. = u ; Had the value of ^ hi a feries proceeding accordiug to the 

dhnenfions of *^ --jC^fcfJx ^^^j ^^^ ^jjj j^^ ^j^^ abfcifs 

A + |i^d:;pxB+iX • . 
required; X denotes the value of ^, when the abfcifs = 4f. 

From the fame principles may the ordinate y^ &c. be found. 

This problem may be refolved in the fame manner, when 
X denotes an infinite ferics deduced from an equation cxprefling 
thie relation between the abfcifs and ordinate of the given 
curve. 

If the given area a be the difFerence between two areas 
SPM (aO and SPQ=i3 (fig.2.) ; for a fubftitute a' - iS, and the 
operation vyill be the fame as the preceding. 

15. I. Given any equations^ of which the increments of 
the quantities contained in them can be found from each other^ 
and given approximate values of each of the unknown quan** 
tities, which nearly correfpond to each other ; to find approxi* 
mations, which differ lefs from the quantities themfeives than 
the given ones. 

Suppofe each of the given approximate values to be in* 
crealed or diminifhed by fmall increments or decrements, as 
tj 0^ I, &c. which are the approximations to be found ; and 
from the given find the equations rcfulting from this hypo- 
thefis ; and from thefe may be deduced, by ftmple equations* 
the approximations fought e^ t\ 0^ &c« by negleding in them all 
the powers of t^ 0^ u &c. except the fimple ones, and all the 
produ£ts of them multiplied into each other ; and confequently 
the equations deduced will contain only given quantities and 
iimple powers of the unknown e^ 1, c^ &c. to be found. 

2. When two or more («) values of one (x) of the unknown 

quantities are nearly equal to its given approximate; then the 

7 equation 



Infinite Strut. i6r 

equation which finds the approximate to x will be a quadratic 
or an equation of n dimenfions* 

3. The approximations found by this method will converge 
more or lefs, according as the approximations given are more 
or lefs near to one value of each of the unknown quantities 
than to the remaining ones, &c. 

Thefe principles were printed in the Medit. Algebr. in the 
years 1768 and 1769. 



L E M M A» 

1 5. Let kah (fig. 3.) be a circle, whofe center is ; and P^ per* 
pendicular to the plane of the circle ; and the force of any cor« 
pufcle in the circle on the particle P vary as the corpufcle 
divided by the {ti) power of its diftance from the particle ; to 
find the attraffcion of the circle kah on' the particle P. 

From the fuppofita the force of any ring contained between 
the neareft concentric circles led and bef of which the center 
is 0^ on the particle P, will be as the area of the ring divided 
by the ;2th power of the diftance ^b \ and con^uently if 
PtfnA, ^6=:% bl-zzv^ and />=* periphery of a circle of which 
the radius is x ; the attra^ion of the ring on P. will be as 

-^i^, and the force of it in the direftion Yo as g xj 
^Ji!l^^, M^^ , q£ ^hjch fluxion the fluent is 

^ ;-; ; and thence the force of the circle M on the 

particle P will be as Jr^^.-^^J—z, f-*^) • 

^ i^nfi^^ i-flPO*^* Vi-»A»-*/ 

Vol* LXXXl. Z Car. 



iSi Dr. Waring on 

Cor. 1. The force of the area contained between the 



two circles ^^^^and led on the particle P will be as — ^ — 



1^. Let a folid be generated by the rotation of a given 
curve round a line in the axis Vo or Po produced, and A the 
diftance of P from o, and ;c=dift:ance of any circle gene- 
rated by the rotation of a point in- the curve round the axis 
Fo from o ; and jy the ordliiate to the given curve, of which the 
abfcifs is x; and the fame things be, fuppofed as before; 
then will the attradlion of the folid on the point P vary as 

/ ' pxA^xxx / . pi \ ^ r pxA-^xXx 

Let the given curve be a circle, of which ,the center Is o^ 
and radius/^ and confequently y=/*-;v% and / !_ ^"^ — -— 



-Sn 



px\-xXx ._p^ 

«— I . (A— **+// * 



»— I . a — 3X{A— i) 



«-ix(A»+i*-2A*y » 

ji-5.»— 3A* « — SA II-5.W— 3xA* ^ 

By fubftituting — / and t for x in the preceding expreffion 
the attraftion of the whole globe on the particle P will be 

«— ^^/j-5 . «-3X A* ^ ^ «-5 . /1-.3XA* 

16. If the particle be (ituated within the globe, and confe- 
quently A lefs than /or — /, and n be an odd number negative 

or 



Infinite Siries^ 163 

or affirmative; or fraflion, of which the numerator is odd; 
then the preceduig refolution will be phyfically juft ; form 
this cafe^ if the attraction on one fide of the particle be affir- 
mative, the attraction on the other will mathematically be 
negative, that is, phyfically oppofite: but if n be an even 
number, or fraction, of which the numerator is an even and 
denominator an odd number, the mathematical folution will 
not agree to the phyfical ; for in the former the force on both. 
fides will be affirmative, in the latter the forces will be oppo- 
fite, and therefore phyfically the force in this cafe will vary as 
L+ H, and not as L-H, which is the force in both the cafes 
when A is greater than / and - 1. The fame may be applied to 
the more general refolution. 

1 7. Let ABCD (fig. 4.) be a globe, of which the diameters AB 
and CD are fituated at right angles to each other, and AHBL be 
a fpheroid generated by the revolution of an ellipfe on its axis 
AB, to which let HL nearly equal to CD = AB be the conju- 
gate, and P a point in the axis BA produced; to find the attraftion 
of the ring contained between the globe and the fpheroid on the 
point P, on the fuppofition that the force of any corpufcle in 
the ring on the particle P varies as the magnitude of the cor- 
pufcle diredtly, and the nth power of its diftance from the 
corpufcle inverfely. 

Let AB =: CD 2= 2/, CD = H L he) + zCH « 2c+ a^ and 
confequently OH = c = /-^ where e has a very fmall ratio 
to /, oP = A, po=x, and pU parallel to CD=^; then, by 
the preceding lemma, the attradion of the circle whofe radius 

is/M on the point P will be =7^"=?^' * *" '"" 
like manner the attraaion of the circle, whofe radius is /w, 

Z a will 



164 D''' Waeiko on 

will be iil^ fyA.-» ^^^ confequently the attrac- 



tion of the riug contatned betvireen the two circles is 
ii-i.PM' * "-» V 









;:p;; — x /+ &c. X** + 



A„ ^ »— 1 X A—xxir— 

&c. =/ X (/ -y j X ■ ~* ^., X * nearly, which rouki* 

(A* + /*-2Ajr/ * 

piled into x, and the fluent of the refulting fluxi(H) found, it 
will be /x(A'+/*-*aJv x((=J — ^J)x' - f^L. +• 

«^5A -^ U-3A^ H-3XA -'^^n-i ,_,A ^ 

r(M). 

If the attraftion of the whole ring contained between the 
fj^ere abd (fhtrdid be required^ fubftitute in the fluent (M) 
for Jt, / and - /, and proceed as in the preceding cafes ; in like ' 
manner may be found the attradlion of the ring contained 
between any two values of x. 

18, The fame principles ntay be applied to find the attrac* 
tion of the above-mentioned ring, when the line P/ is not 
perpendicular to the circles ^M^ pm^ CD, &c^ and does not cut 
the diameters CD, IVfM, &c. into two equal parts. They may be 
further applied for finding the attraftioa of rings coqtained 
between any other givea folids, of which the equations differ 
by very fmall quantities from each other; for example^ 
7 betweea 



Infinite Berks. . 165 

between two fphcroids, of which the axes in the one do not 
difFer much from correfpondent axes in the other, in which 
cafe the fluents found of the following fluxions may be 
ufefuL 

If — 4.» — 5 ^ * ^ 1 II— 4 . « — ft . If— 8 

* «— 4 . »— 6 . » — IJ • . . 3 ^ , 

\!ii «— 3 . Ji-i . 11-7 • «.— 9 . . . 2f^^ * -*' 

. ^JE lLf-ilfTill'?'' X Tj^ if ;i be an odd num. 
ber; but 

z, r * g=.=L-x — f^ — -f .—"-j- X : — f — 



jg— 4 . »— 



; =3E=S 4 ** \»-^ 



+. 



«^3 

^^K»av ^v«^» ''**"o ^M^^B^aaa 

»— 4 • a — 6 . « — . »— 10 . . ■ * 4 * ^ w *^ ;^ » K*^ 

11-.3. a— j.fl-7 ••-g. «- II .... 3. i/"^ {t -^)« 

even. * 

Thefc;,^ priociples may be applied to the finding approxi- 
mations ta very many philosophical problems. 

Cor. I. From hence may be deduced the fubfequent arith- 
metical theorems. 



^*— I 2^11—1.2111—3 2»i— I • 2«i — 3 - 21W— 5 



2m — 2 . 2M — 4 . iw- 6^ ' am — 2 . 2i»— 4 . 2W-— < 



a1w-1.aw-3.aw-i-5.am-7 2)ff-f .am— 3,am-s.a«— 7^.-3. I 

.,; or, which ii ttife toe, ^ + am-T^-i '^' 



1 66 J^r. Warwgm 



^/;i--4X2w-^ 2m — 4 . 2/w — 6 . 2w— 8 . . . 4^ 2 

. rrrr :=r-r^- r^r^-r , , . , + ■ ' ■ «* 

2if2 — 3X2W — 5x2/7;— 7 2w— 3 . 2/w— 5 . 2m— 7 . 2/w— 9 ...3x1 

I , 2W— 6 , 2/« — 6 . 2ot — 8 • - - 4X 2 i 

= I , or ^ + : • • • + ^-== ■ "' ■ — ^ — 

2W-S 2A^--5 . 2/«-7 2OT — S . 2OT— 7 . 2in — 9. . •3X JL' 

» Ij &c. 

I 2w — 3 21/i — 3.2/w — 5 



2«r— 2 2W — 2.2/w — 4 2w— 2 . 2OT— 4 . 2W — 6 

2m— 3 . 2;w— ; . 2/«— 7 

- ■ r K • • • • + 

2m— 2 . 2m — 4 . 2m— 6 . 2m— o 



2///— 3 . 2m— S ■ 2m — 7 . 2m— 9 . • . 7,5 . 

_ ' ' ^ ' o ' ^ + 2 X 



2m — 2 . 2m— 4 . 2/w — 6 . 2m — 8 • 2m— 10 •.•■6.4 
2 m— 3 . 2m — 5 . 2m- 7 . 2m-9 . . * 3 ^ 

2m— 2 . 2m— 4 . zm — b . 2m — 8 . 2m— 10 . . 2 
I , ^^-5 , 2m- 5 . 2m- 7 

2m — 4 2m — 4 . 2m — o 2/» — 4 . 2m— o , 2m— 8 



am--5 ^^2m — 7 . 2 m-Q ■ . > 5 + 2 X 
zm— 4 . 2m— 6 . 2m — 8 ... 4 



2m— C . 2m— 7 . 2m— Q « 2m— II . . > ^ . ^ 



I, &C. 



2/«-4 . 2m-6 . 2f/i— ^ • am- 10 . 2m— 12 ...4.2 

3. By expanding the terms of the preceding fluents may 

be deduced the arithmetical theorems, viz. 

if-4 




x«-7.«"-5.»-iJ*»-i«--^ + >7^-4 + 



I — 4 . n-^b » w — B 



4-. . • • +^==: =^^: == =^ ^»«4«ll.O,., 

' n— o . « — 5 . /J— 7 • /I— 9 . H— II • . • a 

•' a— 3 . B— 5 . B— 7 . «— 9 . a — II • • • 2 



Infinite Series^ t6j 

'iw + c X — 1- =«-- I .«+ I .W + 3.W + 5 ...« + iw + 2x — — 
if /I be an odd number. 



I 



2, K n •- 2. ;i— 1 .« + ! .« + 3 • •• « + 2w+i + 

«-3 



- " " ^ - x;ai-5 ./a — J .«-! ..« + ! •. .« + 2/w - I + 
11-3. «-5 






«— 4. • »— 6 . n — 6 






w — 4..W— 6 .w — 8 • ••2 



«— 3 . »— 5 .«— 7 . «— 9 ... 3x1 

»-i . «+i . « + 3 . « + 5 .. . "+*'" + 3'^^^^» if « be an 

even number. 

4. Arithmetical theorems, fomewhat different, may be de- 
duced from taking the fluxions of the preceding fluents, and 
reducing the fraftions refulting to a common denominator by 
multiplying them into /"-jc*, (t'-xy, (t'-xr)\ &c. 

a-3 ^ »-3-»-5 n —^.n-s-i -J 

■B-3.n-5.w-7. "-9 «-3.a-s.j»-7 .>»-9...2 

^ :iz:;__HLPiir±l"~_^^ •^^— x !^ll^ = o, if » be 
a »-~3 . «— 5 . /< — 7 . A— 9 . »— 1* • • • * * 

odd. . 

2- ^-j'*" '••^7=3. »-5 ' »t-3-"-5-"-7 

^^.«-5-'-7-"-9 „_3.«-5.»-7.'.-9-..3Xi 

jj Izf = 0, if « be even-, or more general, if n be even, 

• * 3- 



/ 



i68 



Dr. Warino on 



3- r=^ 



g — 4,^ — b • n 8* • • B— 2OT— a 



»-3 • «— S • «-"7 • «— Q 



A- 2/91 -3 



X x^ -- 2^ « 4 + 



w— 4- »— b«« — 8 •« — lo« • • /< — 2iri — 4. 



+ 



X(l»-f I X;!r— 2OT — 6— l) 



«— 4 - « — 5 . If— IJ . »— lO . i»— 12 - . • «— 2111 — 6 



n— 3 . « — 5 • « — 7 • «--9 . « — II . «— 13 • • . «— aw— 7 

(_p- — m + 2 " ■ - - -\ 

OT + I . X»-2«l— b^«l+2; + 

1—4 • ||^*.6 « If — 8 * W— IO»«— I2»lf— I4».,. If J 



ii-i-3 . ji-*-5 •*— 7 ••—9 . Ji-^ii •«— 13. Ji~i5 • . •«— am— 9 

23 a / ^ 



— 4 . 11 — 6 . »— 8 • If— 10 • • • • If— am— 10 



X ^«l + I . . — i-d . 

ji— 3 •«— 5 . »— 7 . «— 9» If— 11 *.• »— 2w— II a 3 

^^x;,.am-.i2-^m.!^ .!:i±f) + 



»— 4.n,>5 .11-8 .•..% ^ _^ , 2 . ^-^3 »4-4 
If— 3-*-J««-7 •••3Xi * « * 3 



•-4 



I— 4 . If — 6 . w — 8 • • i»-*ai«— 2 



« — 3 . If— 5 . A— 7 . « — 9 • • »— aiff— 3 

11—4 . w— * If— 8 • • • If— 2m— 4 



X A — 2m — 4 ^ 



w— 4 . If— u • «— o • • • w — 2iff— 4 ^^ / ; — ^ ^ 

» — 3 . «— 5 . If— 7 • If— 9 . . . « — am— 5 ' 

» — 3 • If— 5 , »— 7 • If— 9 • ..»— ant— 7 ^ a ^ 

. \ , If — 4«'»"~^-''-"'»«»«lf"" 2IW— 8 

fW + 2 } + ~ - ' • I — 1 - 11 1 

« — 3 . w— <j . ji— 7 . J1-.5. , • ii— am— 9 

*" + ^ x^ ' ^ _ .^ ' -",^ _ 1: ; T '^ + 3 

2 



x(i»+i .2L±?x 



X«— IW- lO-w + 2, r T ^ ^ 4» ^ 



,r~4>>f-ft>>.-8. y 5x3 /TT-r; m+2 «+3 Jf-S 

i » 4- 3 "» +_4 «— 5 



#w + a 



w+ 4 






»-4 



11-3 . 11—5 • » — 7 . 11—9 . • . 4x2 ^ 3 



II — 



2 — » o, if « be an odd number. 



»-2« — 5 

Many more arithmetical theorems may be deduced from ths 
fluents of thefe and other fluxions by (imilar methods, tvhich 
caunoty without fome difficulty, be found from the common 
methods of finding the fums of feries. 

This method of finding approximations to the areas and 
lengths of curves, fluents of fluxions, and fums of (eries, &c. of 
which the equations, to their increments, fluxions, &c. are given 
from the areas of curves, fluents, &c. of which the equations 
to their increments, &c. differ by very fmall quantities from 
the given equations was publilhed in the Meditat^^ Analyt# 
near twenty years ago. 



I (hall conclude this Paper with two theorems of iome little • 
ufe in the do£lrine of chances. 

tHEOREM I. ^ 






2 



^Zl . IZl a . tf-i . tf-2 . .tf-« + 4X^X^-.i .^-2 + 
a 3 ^ 

a 3 4 ^ ^ 

VouLXXXI. A a n, 



jyo -Dr. Waring on 



^-2 . . .*^ — «+ 2+5 .*-I.^-2.../^-«+I. 

If for ^4-^- I, tf 4-*- 2, ^^ +3-3, &c., ^-1, tf-2, 
&c,, i-i, ^-2, &c. be fubftituted refpeftively tf+5-x, 
tf4.^^2A:, a-^-b^ix, &c., ^-a:, /j — 2^, ^-S-^* &c., ^-;c, 
^ — 2^, ^ - 3.:^, &c., the refulting equation will equally be juft ^ 
and, laftly, if for x be fubftituted o, it will become the bino* 
piial theorem. 

Cor. If there are two different events A and B, of which 
the numbers are refpeclively a and b^ and their chances 
of happening alfo as a and b% and if A's happen, let the 
whole number (^+^) and alfo the number of A's be dimi- 
nifhed by a;, and in the famfc manner of B's happening, and 
io on; then will the chance of A's happening » — / times, 
and B*s happening / times in n trials h^L»y,a . a-^x . a^-zx ^. 
^-(«-/— ij.rx^ . b-x . b'-zx . .b^Q-- i)x divided by H. 

In a fimilar manner may be found, i. the chance of A*s 
happening between h and k times i and, 2. the chance of A*s 
happening (A) to B's happening (k) times ; 3. of A's and B*s 
happening refpedively b and k times more than the other; 
4, the chance of A'^s happening an even to its happening an 
odd number of times, &c« in («) trials, &c. &c. &cr. 



T n £ o R S M II. 



H«tf+^ + ^ + ^+&c. X^ + ^ + ^ + ^+&c. -xxa-^b+c+i 






Infinite Sefiei. tyt 



+ J . d-x + 8cc. + 2ic+26J+2cJ+&cc.) + . . . . +Lx(a. 




d - q -- iJtX&c.*. K) +&C., where L=*».^^—l . llig . 

« 3 

If— /+i _ ;: > «-/— I If— /*^i !!—/-;«+ f 



- — X « - / • — ;; — . . — - — . . :!— X n *-J^ m . 

i 2 % m 



* ;; . - — :; • . . . ^ - X n -^ i ^ m -^ p ^ 

a 3 9 

the fame as the co-efHcicnt of the term afxi^xc^xd^ 

X &c. ia the multinomial a-^b^c + d-k- &c. raifed to the 

power n. 

The chance of any number of event; A, B, C, D, &:c. of 

which the numbers are j, b^ r, d^ &c. happening /, m^ p^ q^ &c. 

times refpe£lively in a Amilar manner to A's and B*s happening in 

the preceding cafe will be i^. 

All the proportion 8 mentioned as immediately deducible 
from the preceding theorem may^ mutatis mutandis^ with the 
fame eafe be applied to more events A, B, C^ D, &c. 

If for tf , b^ c^ d^ &c. be fubftituted the fame letters, in* 
creafed or diminifhed by any given quantitiesi the refulting 
equation will be equally true^ 



A a 1 E It- 



m 



ERRATA. 



VOL. LXXIX. 



ir— I n^2 



Page 171. after +« . . log. r— 3^ + &e. is fimlf/rJhut log. r^n )t 



«— I 



«— I If— 2 



log. r-^p + ft . log. r-^ip^n . • — "Xiog. r — 3^ + &c^=r, wbicb^ 

probably happened, in my abfence from the prefs^ on account of the fimilaritj 
of the preceding quantity. 

Page 17a. 1. x.;%r (dbM+rwi +(Md: 




Ihao4.Tnin4.Vol, iTmnf Xah. K 








JS^fi*%j€ 



[ m 3 



X. jfn jfccount of fome Appearances atteniilng the C^nverp^n of 
cafi into malleable Iron. In a Letter fr(m Thomas Beddoes, 
M. D. iQ Sir Jofeph Banks, Bart. P. R. S. 



Read March 24, 1 791. 



SIR, 



YOU are undoubtedly well apprized of an alteration lately 
introduced into our manufadlories of iron, in confe- 
quencc of which the reverberatory has been fubftituted in the 
place of the finery furnace. The new procefs is capable of being 
indefinitely varied. I have lately been fiivoured with an oppor- 
tunity of obferving one of thefe variations with every advan- 
tage I could defire. As in this naethod the changes undergone 
by the metal during the iirft feries of operations lie perfe£lly 
open to infpeflion, a (hort dcfcriptlon of them may not per- 
haps be unworthy the notice of phllofophical chemifts. 
Allow me to premife further, that I did not content myfcif 
with a fingle examination ; and, for the fake of greater accu- 
racy, I took minutes of the phshomena, and of the time when 
they occurred. A very intelligent workman was at the fame 
time dire£led to anfwer all my queftions^ fo that 1 enjoyed the 
benefit of his experience alfo. 

In fomewhat more than half an hour after it was put in, 
the charge confiiling of zi cwt. of grey pig iron was nearly 
melted. The workman now began to ftir the liquid mafs : 

for 



1 74 -Dr. BsDDoEs onfome Appearanca attending 
for this purpofe he ufed fometimes an iron lever, and fonie^ 
times a kind of hoe; but he firft turned the flame from off 
the metal, which is done by letting down a damper upon the 
chimney correfponding to that with which ordinary reverbera* 
tory furnaces are provided, and by raifing the damper of a 
lecond chimney, which proceeds immediately from the fire* 
place, and carries off the flame, current of air, &c. without 
allowing it pafs into the body of the furnace. 

In 50 minutes from the commencement of the operation, 
the metal had become in confequence of the conftant flirring 
loofe and incoherent; it appeared about as fmall as gravel; it 
was now alfo ftiff, and much cooled. 

55 m. from the fame period, flame turned on again.' Work- 
man keeps ftirring^ and turning over the metal; in 3 m. it 
becomes foft and femi-fluid ; flame turned off; the hotteft part 
of the mafs begins to. h^ave and fwell, emitting a deep blue 
lambent flame. The workman calls this appearance feroien- 
tation. , 

I hour 1 m. blue flame breaking out over the whole mafs; 
heaving motion alio general. 

1 h. 13 m. metal full as hot, or, as the workman and my« 
felf both judged, rather hotter than at the inftant the flame 
was turned off, though it is now a quarter of an hour fince« 

I h. J 8 m. where there is no heaving add no blue flame 
the mafs is fenfibly cooler, and only of a dull red heat. 

I h. 10 m. workman obferves, that the metal flicks lefs to 
his tools* Pig-iron, he fays, iaflens upon it immediately, and 
muft be (haken off by ftriking the other end with an hammer ; 
as it approaches more and more towards nature (malleable 
iron) it adheres lefs ; and when the tools come clear up out of 
the mafs, he judges it to be fermented enough* 

7 I hi 



the Ccnverjion of caji into malleable Iron. 175 

I h. 23 m. little heaving or blue flame ; metal ftlfier, and 
of a dull red ; flame turned on and foon off again. 

I h* 26 m. by conftaut ftirring the metal is become as fine 
as fand. Workman remarks, that the flame, which re- 
appears over the whole mafs, looks more kindly. It is evi- 
dently of a lighter blue colour. 

il h. flame turned on and foon off again. Mafs ferments 
ftrongly. Hifling noife heard : this noife was diftinguifliable 
in fome degree ever fince the blue flame and heaving motion 
became vifible, but always faint till now. 

I h. 40 m. lefs blue flame. 

I h. 48 m. flame twice turned on and off in this interval. 
Metal now clots, ftands wherever it is placed, without any 
tendency to flow, and no liquid pig iron now remains in the 
bafon of the furnace ; the mafs has been conflantly flirred and 
turned over. 

I b. 50 m. a little finery cinder appears boiling up amid the 
mafs. Workman attributes the increafe of the hifling to this. 

I h. ^^ m. fcarce any perceptible blue flame or heaving. All 
the metal is now gathered into lumps, which the workman 
beats and preflfes with an heavy-headed tool. He brings them 
fucceflively into the hotteft part of the furnace, into which 
the flame has been admitted. He now flops the port hole in 
the door at which he had introduced his tools, and applies a 
fierce flame for 6 or 8 minutes ; the metal is then rolled. 

Thefe appearances, at leafl the mofl: intcrefling of them, 
feem to admit of an eafy explanation ; and I offer the following 
obfervations as fupplemental to thofe for which we are already 
indebted to the Swedifli and French chemifls on this impor* 
tant branch of metallurgy. I afliime the following propofi* 
tions as already proved by thefe philofophers. i. That caft 

iron 



176 D^^ Beddoes onfome Appearaficti attending 

iron is iron imperfeftly reduced^ or, in other words, that it 
contains a portion of the bafis of vital air, the oxygene of M. 
LAvorsiER. 2. That it contains a portion of plumbago^ with 
which grey caft iron mod abounds. 3. That plumbago con- 
fids of iron united to charcoal. 4, That fixed air, which I 
would rather call carbonic acid air^ confifts of. oxygene and the 
conftltuent parts of charcoal. 

The heaving or fwcHing motion, io confpicuous in the pro* 
cefs, is doubtlefs owing to the difcharge of an'elaflic fluid; 
and the lambent deep blue flame, breaking out in fpots over the 
whole furface, (hews, that this elaftic fluid is an inflammable 
gas of the heavy kind. That no doubt might be left upon the 
former of thefe circumftances, I diredled the workman to take 
out, at two different periods, a quantity of the metal where it 
was working mofl: flrongly. Both proved, on examination, ta 
be fpungy, cellular, and full of bladder holes. 

The heavy inflammable air, I imagine, is produced in this 
manner. The oxygene of the imperfcdlly reduced metal 
combines with the charcoal to form fixed air ; at the fame time 
another portion of charcoal is thrown into an elaftic Aate, that 
is, into inflammable air, and burns on the fur^ce with a very 
deep blue flame, on account of the admixture of fixed air. 
The heat which is fo obvioufly generated in the mafs at the 
beginning of the fermentation, I attribute to the combination 
of the oxygene and charcoal ; a fad which, with feveral 
otliers as I have already remarked on another occaflon ^, ihews, 
if not the falfehood, at leafl the imperfedlion of the modern 
doftrine on the fubjed of heat. The acidifying principle, it 
would appear, has fome power of generating heat indepeudant 
of its condenfation. Here abundance of elaftic matter is 

* Chemical opiaions of a philofopher of the laft century, 

dif- 



the Ccnverjiin of caft into maUeabk Iron. lyy 

difcharged ; yet« notwlthibnding the heat abforbed by its for- 
matioD, and that which flows out of the metal in all direc<* 
tionSf the whole nvifs becomes hotter. The oxygeue cannot 
be fuppofed to have much fpecific or latent heat, becaufe it 
undoubtedly exifts in the iron in a very condenfed ftatc. Neither 
does the appearance of the mafs allow me to afcribe this gene* 
ration of heat to the burning of the inflammable air at the 
furface, as will alfo be immediately evident for another reafon. 
The lefs deep blue colour of the flame at a fubfequent period 
in the operation is probably owing to the abfence of fixed air» 
or at leaft to its being produced more fparingly, the oxygene 
being now nearly confumed. It will not appear furprizing, 
that the oxygdne in this cafe (hould be confumed before the 
charcoal, if it be confidered, i. that grey iron contains a 
large portion of plumbago ; and, %. that fixed air contains a much 
larger quantity of oxygdne than of charcoal ; near three times 
as muchy according to our beft experiments on its formation : 
fo that I afcribe the fnbiequent fermentation accompanied with 
the lighter coloured flame almoft entirely to the converdon of 
the charcoal into an elaftic fluid. A very experienced philolbr 
pher, I am well aware, has afierted, that water is UQceiiary to 
this converfion ; an opinion concerning the juftnefs of v^hizh 
I have long entertained great doubts. Whenever I have dif- 
tilled charcoal per fe^ I have found the firft portions 6f gas 
to contain fixed air; an appearance owing, as I believe, to the 
decompofition of water abforbed from the atmofphere ; but, 
after continuing the procefs for fome time, there has (till been 
% production of inflammable air ; but from this neither lime« 
water nor milk of lime would abibrb any portion^ though 
when fired with vital or common air, it would produce iixed 
air ; and if moifture was added to the charcoal^ inflammable 
V0L.LXXXI. Bb and 



1^8 Dr. BEtoOEs onjimt Apptarancti aiUnimg 

atid fixed air would be generated anew. Moreover it appears^ 
from the experiments of Dr. Austin and fome others, that 
charcdal confifts of the hydrog^nc and azote of the French 
chemifts. How far it may be difficult or impoffible entirely to 
convert charcoal in its ordinary itate into gas, is a point I wi(h to 
fee more fully illuftrated by future experiments. At prefent it 
ieems obvious, that the circumftances of the operation I hare 
dfefcribed afe particularly favourable to this con veriion : for, i. 
hoc to mention the violence of the heat, we have this fub- 
ftance in a v^xy attenuated ftate, fo that, very probabiy, the 
cxpanfive power of fire is very little, if at all, couiiteraSked by 
the attra£lion of cohefion, which cannot be faid in the cafe o#the 
moft minute mechanical divifion we can efFeA. 2* The attiiac** 
tion of the particles of the iron for one another will prod^ca 
an effort to extrude the intermixed particles of charcoal, and 
thus enable it more readily to^ aifurae che dailic form. 

Now, during the continuance of the T^hter coloured blod 
fianti^i the mafs, as I obferved, ftiews no power of generating 
heat within itfelf ; a circumflance which indicates that thd 
heat produced in the former patt of the operation doefr not 
depend on the burning of the gas at the furface ; and I think 
infpeftion will fatisfy any one that it is producfed in the heart 
of the mafs. It may indeed be obje<fted, that the metal, now 
brought nearer to the ftate of malleable iron, may require i 
grseater fupply of heat to keep it at the fame temperature. If 
is Idfs fofible, aS we are well aflfured. By referring back lathe 
minutes you will obferve, how very often it was necefliary t# 
turn the flame upon the rtiafs during this fecond fermeotatibfil 
in orde^r to keep it in a ftate in which it could be worked. 

The very copious produ<ftion of ehftic flhiids during au hour, 

and often during a much longer fpace, for in this inftance the 

7 procefs 



tie Qmverfiiat of ca/i intd matkaile Iron. t J(^ 

pn)ce& was remarkably fuccefsfui aiid fliort, does not feem 
favourable to a late ingefiious hypothefis, according to which 
water is the embodying priiicipie of all elaftic fluids. I havd 
never indeed oonfidered this as very probable, and, after the ob- 
fervatioos I have related, I fee no means of defending it. Will 
it be iaid, that the pig iron, as being In fome fort a calx of 
iron, contains water ? 

In annealing crude iron, with or without charcoal^ it it 

well known to increafe in all its dimenfions. I have feen bars 

onginally firaight bent like an S, when long expbied to heat in 

circumflaoces where they could not extend themfelves end- 

waysi I fuppcrfc this phfenomenon may be owing to a very 

£mail beginning of this fernientative motion, which afts as an 

inter nai principle of expanfiofi. Caft iron bars, not in conta^ 

^tfa charcoal, would, according to this fuppofition, by long 

annealing lofe of their weight ; or if the heat was too low for 

the elailic flfuid to be 'difcharged from their fubftance, they 

vroold probably blifler like iteel \ an appearance undoubtedly 

owing to the generation of air. Mr. Horne, in his EfTay on 

Iron, <tbmewhere remarks, that oci opening thpfe bliders he 

has lieard a whittling noife as of air rufhiug out. 

During the whole of this procefs, frequent jets of white 
Sparks, of a dazzling brighti^fs^ played fFoai the furface of 
4lie €nel:aL They would have afforded an extremely beautiful 
Ipeftadk but for the inconvenienoe of looking on fo hot a mafs. 
Tbef amfe,. no doubt, from the burning of fmall portions of 
" iron. 

The ^tOi of fo mudi itlirring as I have noted down does not 
tequire to be explained. 

The workman was diearly of opinbn, th^t the fern^enta*- 
tion of hard or white crude iron is lefs than of grey in this 

B b 2 proceis ; 



1 89 Dr. Bbdidoes mfome j^pearanas att€ndwg 

proetfs; a fa^ which perfectly coincides >vitfa the preceding 
obfervationSy iince that fpeciet contains kf$ plumbago, or in 
other words lefs matter fit to produce elafttc fluids. 

lu order to proVe the extrication of fixed air during the 
fermentation of the metal, lonce thought of introducing lime- 
water in an iron veiTei within the body of the furnace ; but 
whehl coiifidefed^hiit the fire-place was not divided by any 
partition from the body of the furnace, and that the whole 
building was full of burned air, I omitted the experiment from 
a perfuafion that, even if the lime-water (hould become turbid, 
the fixed air might come from another fource. 

I was not unmindful of the fulphur which exifts, as I have 
reafon to believe^ iu cyery fiarm of iron manufactured with 
coaks. I cannat, however, afcribc any of the effects 1 ob- 
ferved to its pre(eaee» There can be little doubt, that ibmc 
portion was perpetually extricated with the inflammable air 
during the whole procefs ; for on diflblving pieces of the 
ftamped, or rather the rolled iron in weak muriatic acid, filver 
held in the extricated air was tarnifhed as much and as fooa as 
by air from fpecimeus taken out of the furnace at difiercnt 
times during the procefs. I could not but conclude, that the 
tarnifhing matter came from the iron, when I found the air 
frorn a fblution of zinc in the fame acid, incapable of pro- 
ducing the colour upon filver. The appearance, the wan£ 
of a martial aftringent tafte, and the difliblviug action o£ 
cauftic alkali, led me to conclude, that the colour in each expe- 
riment with iron was derived from fulphur. 

I leave it to the adherents of phlogifbn to accommodate 

thefe phaenomena to their doftrine; confidering it, for my 

own part, as fuperfluous to beflow any further attention upon a 

3 fyftein 



the QimarfiaM'ttf/ea^mh tnaUtaUe tr^, \ t8i 

fyftem which, after a Irag 4ireufliQ0» has been fidlty Tef«bd^m 
all its modifications, afa4 which . indeed feems Oa theeive-of 
being univerfally abandoned.. 

I have the honour to be, kc* 

THOMAS B£J>PO£a. 




[ "«• ] 



XI. On tie Decpntpofitjon of fhedAlr. 
By Smithfon Tennant, Efy. F. R. S. 



Read March 31, I79i* 

AS fixed atr is produced by the combuftion of charcoali it 
has long been thought highly probable that vital air and 
charcoal are its conflituent ingredients. This opinion is con* 
firmed by the experiments of M, Lavoisier^ from which he 
difcovered that the weight of the fixed air which is formed 
during the combuilion is nearly eqqal to that of the vital air 
and charcoal confumed in the procefs ; and that the fmall dif- 
ference of weight may, with great reafbn, be attributed to the 
produdion of water ariiing from inflammable air contained in 
the charcoal. The compofition of fixed air therefore feems to 
be determined, by uniting its conftituent parts, with as much 
certainty as by that mode of proof alone it is poilible to ob- 
tain. But as vital air has a Wronger attradion for charcoal 
than for any other known fubftance, the decompofition of 
fixed air has not hitherto been attempted. By means, how«> 
ever,, of the united force of two attradions I have been able 
to decompofe fixed air, and thus to determine' it^s conflituent 
parts in confequence of their feparation. 

It has long been known, that when phofphoric acid iscom« 
bined with calcareous earth, it cannot be decompofed by dif- 
tillation with charcoal : for though vital air is more flronglj 

attraded 



Mr. Tenn ANT M the Deeompofitkn offoced Air. j g j 
attraded by charcoal than by phofphorus, yet in this com- 
pound it is retained by two attradions, by that which it has 
for phofphorus, and by that which the phofphoric acid has for 
lime, iince the vital air cannot be difen gaged anieis both thefe 
attradions are overcome. As thefe attractions are more powfer* 
ful than that which charcoal has for vital air, if phofphorus is 
applied to fixed air and calcareous earth, the vital air will unite 
with the phofphorus, and the charcoal will be obtained pure. 
Thefe fubftances, in order to aft upon each other, muft be 
brought into contaA when red-hot ; and this may be ea(ily 
effeded in the following manner. Into a glafs tube» clofed at 
one end, and coated with fand and clay to prevent the fodden 
adiion of the heat^ a little phofphorus (hould be firft intro* 
duced, and afterwards ibme powdered^marble. The experi* 
ment fucceeds more readily if the niarbie is (lightly calcined^ 
probably becaufe that part which is leduoed to lime^ by imme- 
diately uniting with the phofphorus^ detains it to aft upon the 
fixed air in the other part. After the ingredients are intro« 
duced, the tube (hould be nearly, but not entirely, clofed up ; 
by which meaiks fo free a circulation of air as might inflame 
the phofphorus is prevent^y whilft the heated air within the 
tube is (ufiered to efcape. When the tube has remained red^ 
hot for ibme m'mutes, it may be taken from the fire, and muft 
be fv^ered to gr^w cold before it is broken. It will be found 
to contain a black powder, confifting of charcoal intermixed 
with a compound of lime and phofphoric acid, and of lime 
united with phofphorus. The lime and phofphoric acid may 
be feparated by folution in an acid and by filtration, and the 
phofphorus by fublimation. 

Charcoal, thus obtained from fixed air, appears in no refpeft 
to differ from the charcoal of vegetable matters. On deflagra- ^ 

ting 



1 84 Mr. Tbnnant on tbe Deeompt^ion of fixed Air. 
ting a little of it in a fmall retort with nitre, ^fixed air was im« 
mediately reproduced.— Since, therefore, charcoal, by its repa- 
ration from fixed air, is proved to be one of its couftituent prin- 
ciplesi it can hardly be doubted, that this fubftance is prefent 
whenever fixed air is produced ; and that thofe experiments, 
from which it is fuppofed that this acid may be formed without 
the aid of charcoal, have not been conduced with the requifite 
caution. 

As vital air is attra£ked by a compound of phofphorus and 
calcareous earth more powerfully than by charcoal,'! wasdefi* 
rous of trying their efficacy upon thefe acids, which may from 
analogy be fuppofed to contain vital air, but which are not 
afiedted by the application of charcoaL With this intention I 
made phofphorus pa^s through a compound of marine acid and 
calcareous earth, and alfo of fluor acid and calcareous earth, but 
without producing in either of them any alteration. Since 
the flrong attra^Etion which thefe acids have for calcareous earth 
tends to prevent their decompofition, it might be thought that 
in this manner they were not more difpofed to part with vital 
air than by the attraction of charcoaL But this, however, 
does not appear to be the fad. I have found, that phofphorus 
cannot be obtained by paffing marine acid through a compound 
of bones and charcoal, when red-hot; The attradion, there^ 
fore, of phofphorus and lime for vital air exceeds the attradion 
of charcoal by a greater force than that arifing from the attrac- 
ttion of marine acid for lime. 






C '85 ] 



XIT. A Meteorological Journal principally relating to Atmo^ 
Spheric EleSlriciiyi kept at Knightfbridge, //o/w the ^th of 

.. May, 1789, totbeSth o/M^y, 1790. i[y Afr. John Read ; 
communicated by R, H. A. Bennet, Ef^. F. R. S. 



Read April 14, 1791. 

A DESCRIPTION of the Inftrument for colleaing atmo- 
ipheric eledricity, ufed in the following journal. 

Tab. V, reprefents the apparatus. AA is a round deal 
rod, 20 feet long, % inches diameter at the lower, and one inch 
9t the upper end. Into the lower end of it is cemented a folid 
glafs pillar B, 22 inches long; the lower end of the glafs 
fiands in a hole made for it in a pedeftal of wood C, which 
flips on the fore-part of an iron bracket D, which is driven, 
into the wall, and fupports the whole. About 13 feet above 
the bracket D, is fixed to the wall a ftrong arm of wood £, 
which holds perpendicularly a flrong glafs tube F, through 
which the rod is (lidcd gently upwards, till the glafs pillar B 
may be lowered into the hole made for it in C. It is thus 
fixed, and flands 1 2 inches from the wall. The tube F is of 
fufficient width to admit a cafe of cork, which is failened in 
the iniide of it, at the part where the tube is fuftained by the 
arm of wood E, fo that the rod, when bent by the wind, cannot 
touch the tube or break it. The upper extremity of the rod is 
terminated by feveral (harp-pointed wires G. Two of them are 

Vol. LXXXI. C c of 



1 86 Mr ^ Re AD^s Metiorologlcal Journal 

of copper, each one-eighth of an inch thick ; and, in order 
to ftiffen the rod, as well as condud more readily the eledric 
fluidy one of thofe wires is twifled round the rod to the right 
band, and the other to the left, as low down as the brafs 
collar at the vertex of the lower funnel H, to which they arc 
ibldered, in order to render their contad perfed. The tin 
funnels HH ferve to defend the glaffes B and F from the wea- 
ther, which glaffes are alfo Covered with fealing-wax to render 
their infulation more perfedt. At a convenient height from the 
floor, a hole is bored through the wall at h This hole receives 
a glafs tube covered with fealing-wax, through which a ftrong 
brafs wire proceeding from the rod is conveyed into the room^ 
where jufl at the end of the glafs tube it pafies through a two- 
inch brafs ball t/, and proceeding a little ^rther, keeps fuf^ 
pended at its extremity a pith ball eledrometer K, fo that the 
electrometer may be about twelve inches diftant from the wall. 
On the outiide of the wall ther^ is a' wooden box M, to keep 
that end of the glafs tube dry,. 

At two inches diftance of the above-mentioned brafs ball L, a 
bell N is fupported by a flrrong wire; which pafling through 
another hole made in the wall, is made to communicate, bjr 
means of a gpod metallic continuation R, with the motft" 
ground adjpining to the houfe* A brafs ball, three-tenths of 
an inch* in diameter, is fufpended between the bell N and ball 
L, by a (ilk thread failened to a nail O. This ball ferves for a 
clapper, by ftriking hetween the ball and bell, when the tltd:n^ 
cal charge of the rod iis fufficiently ftrong. 

P is a.fmalltable ffxed to the wall under the beirand'ball, at 

a convenient height above the floor, upon which Leyden bottles 

and other apparatus are occaiionally placed; Any perfbn verfed* 

in the fcience of elcdtricity, will eafily undwftand that this 

6 apparatus^ 



. relating to Jkmo^heric EhSrichy. 1.87 

apparatus is caiculattd to ihew the various degrees of atmo- 
ipherical eleAricity, and at the iaaie time to avoid the perni- 
cious efTeds which may be occaiioned by thunder^-flormSf or 
in flio'rt by any great quantity of eledlricity in the atmofpherc. 

The whole perpendicular height of both parts taken toge* 
thert from the moid earth to the uppermoft point at the top of 
the rod, is 52 feet. 

Finding, however, that> notwithftandlngall.the precaution I 
had taken to procure a good infulation, the moid vapour 
of the atmofphere, fixing upon the infulating parts of theappa^* • 
ratus, rendered it imperfedt in moid weather; I have lately 
(15 th of Sept. 1790) altered the (ituation of the fame rod, fo 
that all the infulating parts are now within the roof of th^ 
houfe. This I have effected by a hole through the roof of my 
houfe; by which means I now obtain a contiderably mor:p 
conilant electricity ; which^ however, mud not be folely attrir 
buted to the fuperiority of my prefent mode of infulating., but 
to the rod*s being alfo elevated to the additional height of nine 
feet; fo that I confider its pointed part to be at prefent 61 feet 
above the moid earth. . ' 

This improvement of the apparatus, having been made after 
the conclufion of this journal, will be particularly defcribed 
in the next, which I am now carefully continuing* 

It will be necefiary jud to mention the method 1 have purfued 
in forming the journal of atmofpheric electricity. This has been 
principally by oceans of the figns exhibited by the pith bal|s K, 
connected with the rod. When I find thefe doled, and not 
attracted by my finger, I then write no figns pf eleCtricity. 
When attracted on the approach of my finger, yet not fuffi- 
dently charged to repel each other, I write weak figns of the 
fluid. When I find the balls open, and, on the approach of 
eKcited glafs, the balls clofe, I write they are cledrified pofi- 

C c a tively ; 



1 88 Mr. Re AD^s Meteorological Journal 

tlvely ; but, if the balls open widert I write they are eleArified 
negatively; aiid the reverfe when I ufe fealing-wax. When 
the balls diverge one inch and upwardsy vifible fparks may be 
drawn at the brafs ball L. When fparks are faid to have bee^ 
perceived in any obfervation, I have generally on that account 
omitted to note the variable quantities of divergency in the 
pith balk. Their utmoft limit of regular divergency feems to 
be about five or near fix inches ; above that they are unfteady 
and diforderly. The pith balls are near two-tenths of an inch 
in diameter, fufpended by very fine flaxen threads (in the ftate 
it is in from the heckle) five Inches long. When I mention 
the diftance of the balls in tenths of an inch, it is to be un- 
derftood as nearly fo as my eye can determine. 

This apparatus requires a conftant attention, efpecially during 
a difturbed flate of the atmofphere. From the room in which 
the apparatus is placed I am feldom ablent one hour, excepting 
the time of fleep ; but, when I leave it, the laft thing I do at 
night is to examine the ftate of the eleAricity, and, if I find 
the rod uneleftrified, I then place the Leyden bottle on the 
table P, with its knob nearly in contad with the ball L. The 
next morning, if I find this bottle charged^ I write the kind of 
eledlricity it is charged with againft the day in the journal, and 
add, 6y the night Bottle. 

It is prefumed, that the table is fufficiently obvious. The 
two columns for pofitive and negative elcftricity are ufed only 
for the firft obfervation of each day. I ufe Fahrenheit*s 
thermometer, fufpended on the north outfide of a bow win* 
dow. The time of making the obfervation with it, and the 
barometer, and alio of the diredion of the wind, has ufually 
been about nine o'clock in the morning. 

Laftly, it may be ufeful to obferve, that I have always 

found the lower though uniufulated part of the apparatus (vi%. 

3 the 



relating to AtmoJ^beric EleStricity. 189 

the metallic coone^lioQ of the bell N with the moift earth) to 
be in a contrary ftate of eleAricity to the upper and infulated 
part, where the pith balls K are fufpended. See the 22dof Aug» 
Having made a memorandum of the feveral thunder- 
fiorms which have happened in divers parts of this ifland, 
according to the information by letters, and from news- 
papers, I thought it ufeful to infert them in this journal, in 
order to (hew whether fome contemporaneous appearances in 
my apparatus might not be attributed to them. This feems 
evidently to have been the cafe on the 3d of September. 



Days, 


Wnd, 


Barom. 


Ther. 


Sparks. 


Pof. 


Ncg. 


May 9, 1789. 






Inches. 













May 9 


NW 


30. 


63 


. 




ncg. 


Balls open about thrcc-tcnihs of an inch. 


10 


sw 


30-15 


60 







ncg. 


But very weak. 


II 


£ 


30.24 


61 





— 


neg. 


Barely fufficienc to feparate the halls. 


12 


£ 


29.91 


60 


fmali 


^ 


ncg. 


The firft day I have had vifiblc fparks ; 
weather cloudy, but fair. 


13 


£ 


29.91 


61 


ftrong 


pof. 




The weather in the forenoon a little 
hazy ; in the afternoon a thick fog ; 
four o'clock a little rain fell ; the rod 
now became highly cle^rified pofi- 
tively ; the bell rang briikly. I now 
filled feveral bottles with the fluid. 
This flrong charge in the rod did not Lid 
longer than one hour, but it remained 
charged pofitivcly in a id's degree the 
reft of the day. There was this day 
fome lightning and thunder at Salif- 
bury, and to the weft of it. 


H 


SE 


3°- 


56 





pof. 


.— 


Balls open four-tenths of an inch. 


15 


E 


29.66 


58 


fmall 


pof. 


— 


A.M. and P.M. negative. 


lb 


SE 


29.83 


61 





-. 


ncg. 


A.M. and P.M. 


17 


S 


29.91 


58 





— 


ncg. 


Balls open (ix-tcnths of an inch. 


18 


SW 


29.91 


57 





— 


ncg. 


Balls open five-tenths of an inch. 


*9 


N 


30.20 


54 





— 


ncg. 


P.M. dark heavy weather. 


20 


SE 


3015 


S6 


fmall 


— 


ncg. 


The rod was electrified nearly th^ whole 
day. 


21 


E 


30. 2 


54 





— 


ncg. 


Nearly the fame as the preceding day. 



May 



lya 



Mr. Read** Mtteorohgkal Jtmrnal 



Days. Wind. Barom. Thcr.jSparks. Pol. Ncg. 



May 22 

24 
as 



27 
28 



29 



30 
31 



June I 



S 

• S 
SE 
£ 



26 NE 
SW 
SW 
W 



S 
SW 



SW 



iDches. 
29.89 
29.90 

29-75 
29.68 



29.64 
29.6c 
29.86 
29.72 



29.70 
2957 



29.71 



58 

59 
60 

62 



61 
60 
60 
61 



S6 

58 



53 



o 
o 
o 
o 



o 
o 

o- 
firong 



o 
fb*ong 



pof. 
pof. 
poi. 



pof. 
pof. 



pof. 
pof. 



ftrong 



pof. 



ncg. 



ncg. 
ncg. 



) 



Juft fufiicient to 
Serene weather. 



indicate the kind. 



Six o'clock A.M. Soon after a fog with 

I drizzling rain, by which the rod be* 
came charged pofitiTcIy. 

'A.M. 

I A.M. Ballf open three^tenths of an inch 

.But very weak. 

A very cloudy morning, though at too 
great a height for my rod ; but in the 
afternoon the clouds approached much 
nearer^ and the rod became charged 
pretty ftrongly pofitive, which conti- 
nued about one hour and a quarter, 
I charged fome Leydcn bottles with 
the fluid, fome podtivc, -others nega-j 
tive, for there were four gradual 
changes of the eledricity. 

Balls opi^n half an inch. 

Nine o'clock A.M. a heavy ihower of 
rain fdl, the rod bccanie (b-ongly 
charged with negative eledricity, all 
the time the ihbwer laded, which was 
fliort and fudden. One hour after- 
wards, the electricity changed to \ 
ftrong pofitive, the bell fuddenly be- 
gan to ring, and continued to do fo 
five minutes ; the pith balls then clofe 
flowly, and open negative, and conti 
nued weakly fo the reft of the day. 
At Edinburgh, ibme lightning and 
thunder this day, 

A cloudy fhowcry morning. The eledric 
charge in rod was moft beautiful this 
day. In about fix hours time I ob- 
ferved feven changes of the eledricity ; 
five of thofe changes were gradual. 
The balls opened from 3 to 4 inches, 
and remained fo from 15 to 20 mi 
nutet each opening, then gradually 
clofed ; the other two charged flowly, 
but clofed veiy quick. 



June 



Tikting t$ AtmQfphtric ElfSrkity^ 



t^t 



Days. 



Wind. Barom. Then Sparks. Pof. Ncg. 



June 2 
3 



SW 

sw 
w 



I 



8 
9 

lO 

II 

12 

•3 
14 

*5 

t6 

17 



NW 
W 



NW 
NW 
NW 
NW 
NW 

B 

E 
N£ 

B 

£ 
S 



ilnche*. 
29.85 
29.92 
29.42 



29.5a 
29.78 



99.9a 
30.18 
jaia 

J0.12 

30.25 
30.28 
30.19 

30. 4 
29.90 
29.81 






S3 
S3 



sa 

S7 
56 
5S 

56 

54 

sr 
5$ 

62 



o pof, — But weak. 

O pof. — A.M. 
ikrong pof. -— A cool cloudy morning. The rod was 
pretty ftrongly elec^trified full fcven 
hours to*day, the reft of ihe day but 
weakly fo There were 12 changes 
of the electricity, all gr^^dual, except 
one, which was inftantancous ; the 
balls fometimes exhibited a waving 
motioOy and fometimes fudden jerks. 
There were fcveral ihowers of rain, 
and two of hail; during the fall 
of hail, the rod was moft powerfully 
ele^rified, the bell rang very flrongly ; 
the effects and appearances were fo 
awfuly that I kept at a good didance 
from the rod. A great deal of light 
ning on the eafi fide of Kent and EiTex 
this day. 

O *-" neg* Balls open half an inch. 
ImaU -— neg. A.M.and P.M. pofitive; there werefmall 
^arks emitted from the brafs ball L, 
and the pith balls continued clofing 
and opening many times, without any 
change of kind, for full two hours. 



o 
o 
o 
o 
o 
o 
o 
o 

o 
o 

ixOBg 



pof. 
pof. 



pof. 



neg. 
neg. 
ncg. 



neg. 

ncg. 
neg. 



. Balls 'open from one to feven- tenths 
of an inch.* 

Weak figns, balls not open. 

Balls open three-tenths of an inch. 

Balls open five*>tenths of an inch. 

Very cloudy weather, but at too great 
a height to affett the rod. 

Balls open full half an inch.. 

Balls open near one inch. 

Ten o'clock A.M. a fudden Ihower of 
rain fell, by which the rod became 
highly ele£^rified pofittvely, and con 
tinned to emit fmall fparks at the bail 
L, long after the ihower was over, 
without any change of the electricity 



June: 



t^2 



Mr. Read*s Meteorological Journal 



Days. Winds. 3arom. Thcr. Sparks 



Pof. Neg. 



JUQC 1 8 



SE 



19 SW 

20 sw- 
at SW 



Inches. 
29.89 

29.88 
29.65 
29.71 



22 

*4 



SW 
SW 



SW 



29.49 

^9-54 



60 

S6 
63 
59 



S6 

57 



29 60 61 o 



fmall 

o 
o 
fmall 



fmall 
fmall 



pof. 



pof, 
pof. 



iThe weather ihowery ; the rod pretty 
well elcArified. 

oeg. Balls open fix-tenths of an inch. 
Weak figns ; balls not open. 

neg. This momingfeveral heavy clouds paifed 
over, c6ming from the SW, by which 
the rod became moderately eledtrified 
negatively. Some rain fell, which 
increafed the eledrical charge. But, 
in the afternoon, the wind and clouds 
put on a more ominous appearance ; 
near five o'clock, began a florm of 
wind, rain, lightning, and thunder; 
but the main weight of the ftorni did 
not come near my rod. Its dire effects 
mud be eaft of London : nererthe- 
lefs, I had thofe ufual beautiful ap< 
pearances which attend a ftrong charge 
in the rod. The fiorm lafied one full 
hour, during which time there were 
five fucceffive changes of the dedri- 
city, vi%, four gradual ones, attended 
with fudden jerks or ftarts, which 
often diminifhed the divergency of the 
pith balls from 4 inches to 2 inches or 
lefs. After thofe jerks the pith balls 
recovered their former degree of di 
vergency, fometimes fuddenly, and at 
•ther times (lowly. The other change 
happened ioftantaneoufly, the pith 
balls collapfing and opening fo quickly, 
that the eye could barely fee their mo- 
tion. There were two other inftan* 
taneous clofings and openings of the 
balls, without a change of the ele^^ri 
city. Much lightning at Gravefend 
to-day. 
'The rod was in charge all day. 
Moft of the forenoon. Afternoon ibme 
rain fell, and the rod became ele^ri- 
fied negatively, and ended pofitively. 

neg. |A.M. ^ 

June 



relating to Atmfphertc BteStncity. 



i9j 



Days. 



Wind, Baroin. 



Thcr. 



Sparks.! Pof« :Ncg. 



June 5^5 



NW 



a6 W 
27 W 



aS 



ft9 

a 
3 



6 



W 



w 

NW 

N 
N 
N 

N 

N£ 
N£ 



Inches. 
29.64 



29.80 
29.96 



^9.70 



29.90 

36-10 

29.19 

30.3 

30.2 

30.2 

29.19 
29.17 






SS 



53 

5^ 



ftrong 



6 
ftrong 



S<^ 



ftroBg 



53 

76 
79 

80 

74 
72 



ftrong 



o 
o 
o 

imall 

o 
finaU 



pof. 



pof. 

pof. 
pof. 



ncg. 



neg. 



ncg. 



neg. 



neg. 



A very thick cloudy morning. The 
cle^ric charge in the rod has been mo- 
derately ftrong and very fine to-day 
There were five gradual changes of the 
elcdricity. 

A.M. 

Cold fiioweiy weather. Except fome 
fmall intervals, the rod has been 
ftrongly eleftrified all this day. The 
bcfi once rang bri&ly for a few mi- 
nuces, then fuddenly Itopped its ring 
ing ; the pith balls clofed and opened 
negatively, and continued fo till a little 
after eight o'clock P.M. when they 
changed to pofitive. At Liverpool, 
this day, a tremendous fiorm of light- 
ning, thunder, hail, and rain. 

A very cold morning and fliowery, the 
drops of tain were very large. The 
rod has been very powerfully ele^ri- 
fied near twelve hoirrs this day, during 
which time there happened eleven 
changes of the ele6)fricity, all gradual 
but one. The balls often exhibited a 
waving pendulous motion, tvithout 
any diminution ih their divergency. 
There were alfo a few of thofe jerks 
before noticed on the 21ft inl^ant. 

The bell rang brifkly. There' was no8 
change of thie eledricity. 

Nearly all day. Weather fefene and 
clear. 

}Weak figns, balls not open. An eveoj 
darkflcy, but fair. 
Weather fereoci very hot, and a cleat 

.iky. 

A.M. and P.M. negative. At Glaf- 
gow, fome lightlying and thunder. 

Weak figns. Balls not open. 

A heavy dark afmofphere, but fair. 
At Monkfilver^near Bath» mi(ch light* 
ning and thunder. 



Vox.. LXXXI. 



Dd 



Jul7 



194 



Mr. Read^s Meteorological Journal 



Days, Wind. 



Baroxn. 



July 



9 

lO 

II 

12 

^3 



14 
IS 



i6 



i8 
19 

20 



NE 
NE 
NE 
NE 

E 

E 
W 



sw 

NW 



w 

sw 



sw 
w 

NW 



Thcr.Sparks. 



Inches. 
29.16 

29.20 

29.15 
29.13 

a9- 5 



29. 6 
28. 8 



30- 
29.10 



2915 
29.10 
29.10 



69 
60 
72 

72 

74 
78 

72 



69 

60 
65 



59 

SO 



Pof. 



eg. 



o 
o 
o 
o 

o 

o 

fmall 



o 
fmali 



o 

fnuU 



o 

o 

ftxong 



ncg. 
ncg. 

ncg. 



ncg. 



peg. 



ncg. 
ncg. 



1 Weak figm of electricity; bidU not 
J open, 

A.M. 

A.M. 

BalU not open. 

A.M. and P.M. pofitive with fparks 
At Hereford, this day, a ftorm of rain, 
light ningy and thunder. 

Weak fjgns ; balls not open. 

A.M. and P.M. pofitive, with bright 
fparks. At Strichcn^. in Scotland, 
heavy thunder fiornn. 

Balls not open. At Edinburgh, this 
day, fome lightning and thunder. 

P.M. fine fparks ; no change of kind. 
At Glafgow and Hamilton, this day, 
lightning, thunder, hail and rain 
and alfo at Newcaflle, in Northum* 
berland, the florm was fevere. 

Weak figns ; balls not open. 

P.M. 

Three o'clock' P.M. I faw a thunder 
itorm approaching. While the ftorm 
remained at a conflderable diftance, 
the rod was very highly charged with 
negative eledricity, and continued fo 
three quarters of an hour; during 
which time diftant thunder was heard, 
Sometimes the balls were affeded with 
a jerking, at others a waving, nootion. 
The wind now ihifted to the SE, and 
a heavy rain foon came on ;: thC'eledh- 
city now changed to pofitive, and the 
beU now rings briikly; erery appear- 
ance (both within and without the 
room; was tremendoufly awful. I 
therefore feated myfelf upon a larg^ 
in&lated. fiooi, where I could with 
fafety obferve the apparatus. A Ley 
den bottle was undefignedly placed 
with its brafs knob near to the brad 



July 



nlaimg to AtmoJ^heric EleSridty-. 



'95 



Dayi. 



Wind. 



Barom. ITher. Sparki. i Pof. Neg. 



July 21 



vx 



SW 



«w 



23 
26 



w 
w 

W 

w 



Incbe*. 



29- »5 



29.10 



29.10 

2915 
29.20 
29.10 



Sa 



61 



51 

71 



firong 



ftrong 



ftrong 

iinall 
O 
o 



pof. 



neg 



neg. 



iicg. 



ball L. This bottle charged and fpon 
taneoufly difcharged ahnoft as quick as 
I could notice them ; and at the fame 
time there was a continual flafliing 
of denfe fparks between the bell and 
brafs ball L. Thefe very grand appear- 
ances only lalled ten minutes, and the 
fcene was terminated by a clap of 
thunder; but the ftorm, and its effe^s 
on the rod, lafted near two hours. I 
faw no lightning but what was in the 
apparatus. There were nine gra^iual 
changes of the electricity, from nega- 
tive to pofitive, &c. 

had purpofely placed a large glafs 
bowl, upon an infulated table, in the 
open air, to catch the falling clc6lri 
fied rain. As foon as the bottom of the 
bowl was well covered with the rain wa- 
ter of the above ftorm, to my great fatif- 
fadion, a pair of linen threads I had 
placed for the purpofe diverged near 
two inches ; the water remained elec- 
trified near tea minutes after it was 
taken into the houfe. 

P.M. a little rain fell, and the elcftri- 
city changed to pofitive. At Edin- 
burgh and Bamff, this day, there was 
much lightning and thunder. ' 

A very firong elcdtricity in tbe rod all 
the forenoon. 12 o'clock feme rain 
fell, on which the rod became highly 
charged pofitively, the btll rang 
weakly for a long time, it then flop 
ped, and the balls clofed, aDd opened 
negative, and continued 'fo full three 
hours. This day, near Shrewfbury, a 
ilorm of rain, lightning, and thunder. 

Both A.M. and P.M. and ended nega- 
tive as the preceding day. . 

A.M. and P.M. pofitive. 

}Weak figns; balls not open. An 
uniYcrfal cloudy dark (ky^ 



Dd 



July 



jptf 



Mr. RsAii^s Metitorohgicai Jouriiti. 



Dayt. 


Wind. 


Baroiu. 


Ther. Spark*. 


1 
Pof. Neg. 


I 






Inches. 













jjuly a; 


•N 


29.15 


64 


ftrong 


•^ 


neg. 


Four o'clock P M. happened a fiidden 
and fliort floroi of wind and rain. The 
















rod became powerfully ele^krified, the 
bell rang for 20 minutes, then ftopped, 
and the eledricity became pofitive, and 
ftrong. At Cambridge, this day, a 
tremendous ftorm of lightning and 
thunder. 


28; N 


29.20 


5^ 





pof. 


— 


A.M. balls open five-tenths of an inch. 


29 W 


30- 


iinall 




neg. 


A.M. 


30; NW 


29.30 


73 








neg. 


Balls open (ix-tenths of an inch. 


3' 


W 


29.20 


75 







neg. 


P.M. a regular dark Iky, with fmall 
rain, which iafted four hours; fuch 
rain is never eledtrified ftrongly. Aii 
is very moift. 


Aug. I 


W 


29.79 


60 





— 


— 




2 


w 


30.12 


5* 





— . 


_. 


A heavy dark atmofphere, and a 


3 


SE 


30. 


62 





— 


— 


^ warm foft air. The eleftricity thcfc 


4 


£ 


3P- S 


61 


'O 


— 


— 


ilx days amounts only to weak iigns^ 


S 


E 


2979 


66 








— 


balls not open. 


6; sw 


30- 9 


60 





— 


— 




7 


W 


3027 


S6 








neg. 


P.M. 


8 


W 


30.24 


58 








neg. 


A.M. 


9 


E 


30.20 


66 








neg. 


A.M. 


10, E 


30- «7 


60 





— 


neg. 


A.M. 


i-i 


NE 


30.20 


66 





•— . 


— 


Balls not open. 


»a 


E 


30.16 


S8 


flroog 


pof. 




P.M. a fine (hower of rain, on which 
the rod became pretty well eledlrified ; 
but ibon changed to a muck more 
ftrong negative eledricity, which af- 
forded fine fparka at the brafs ball L. 






























The pich balls niany timesclofed and 
















opened, without any more changes 
















of kind. 


13 


E 


30.14 


60 


ikiall 


pof. 


-. 


A.M. 


14 


NE 


3o»3 


6a 





pof. 


— - 




»S 


NE 


30- 9 


59 


ftixmg 


pot 




A.M.F.M.a very black cloud paffed cnrei 
thcTOdfbywhichtt became leiy ftiongiy 
eledrificd for a few mimtei only; 
the bell rang brifrly. 


16 


N 


30'»S 


6s 


firoog 


pof. 


•^^ 


There hat been much rain to^dayy and! 
thedrops very large. The rod bat beei4 



Aug. 



nbtffftg fp Jitmo^ent EUSrkU^» 



>9r 



Dajs. Winds. Barom. iTher. 



Sparks. 



Inches* 



Ang.17 
18 

20 
21 

21| 



N£ 
NE 
N£ 
£ 
S£ 



30.06 
30«32 
30.2s 
29.9s 
29-75 

«9*75 



61 
6x 
60 

63 

63 

56 



Pof. 



N€g. 



fmall 
o 
o 
o 

fifPD{ 

ftrofig 



ncg. 
ncg. 



ncg, 
ncg. 



in highcharge great part of the day.The 
fparks at the brafs ball L were very pun 
gent ; even the air in the room, and the 
uninfulatcd beli^ and other things, 
Ihewed that they were ele£lrified. The 
bell rang brifltly at three very different 
times. This ftrong charge of the rod 
continued full four hours; and the 
electricity, during that time, changed 
in kind ten times. Eight of them 
were gradual, two of them were 
quick, and attended with jerks, 
heard fome rumbling of thunder at a 
great diflance. At Dtmwich, in Suf- 
folk, this day, much lightning and 
thunder. 

A.M. 

Balls open nine^lenths of an inch.. 

Weakfigns; balls not open. 

P.M. a ftreng charge in the rod, but 
of (hort duration. 

The rod was in lu|^ charge ten hours 
this day, except a few fmall intervals ( 
there were nine gradual changes of the 
eledlricity, from negative to- pofitive, 
and the contrary. . The bell rang very 
brilkly at three different times during 
that period. There were feveral 
(howers of rain, and one pf hail ; 
during the latter, the electric charge 
in the rod was moft intenfe; the 
fparks darted between the ball and bell 
extremely fharp and quick. I found 
the moifture in the air of the room 
was now eledrified, alfo the bell, and 
i(t8 metallic connexion with the earth, 
and even the bricks in the wall to 
which the metal is faiUned were all 
electrified with an electricity contrary 
to that in the iofsiated part of the ap* 
paratus. An eleCtrician (who had 
often in vain called at my houfe to fee 



Aug.. 



198 



Mr, Read*8 Meteorological Journal 



Day». 



Wind*. 



Barom. iTher. Sparks. 



Aug.as 

2 

28 
29 

3» 



Inches. 



W 

NW 
SW 

sw 

N 

w 

SE 
SW 
NW 



a9.94 



Sept. I 

a, 

3 



SE 
S 

s 



30. 8 

30- 3 
29.QO 

29.80 
a9-7S 



29.72 
29.60 

29.50 



5* 



30- »5 
30.19 

30.10 58 



58 
60 



59 
54 
58 
60 
62 



Pof. Neg 



58 
66 

69 



firoBg 

ifliall 
o 
o 

o 
o 
o 
o 



pof. 

pof. 
pof. 



pof. 



neg. 



o 
imall 

fmafi 



pof. 
pof. 



neg. 



the apparatus in high charge) placed 
his left hand on the bell, and with his 
finger of the right hand approached 
the baH L ; a denfe fpark iflued to it, 
and he recei^d a fmart ihock in his 
arms and bread, like that of the Ley- 
den bottle. We then joined hands, and 
made the circuit in the ufual way, be* 
tween the bell and ball, and we both 
received a fevere Ihock. Much light< 
ning and thunder this day at Stirling 
and Dumfries, in Scotland. 

A.M. and P.M. negative on a fall of 
rain. 

Great part of the day. 

A.M. but irery weak in the afitemoon« 

Weak figns ; balls not open. 
AM. a ferene clear iky. 
Only weak ilgns. 

P.M. from a fhower of rain, the drops 
of which were very large. The elec- 
tricity foon changed to pofitivc 
Though every circumfiance was fa* 
vourable for a ftrong eledrification, 
yet the charge in the rod was but weak. 
My fufpicion led me to try the ftate 
of the uppermoft end of the rod> and 
I found it to be m a contrary ftate of 
eledricity to that at the lower end 
of it ; theoiiddle part of the rod was 
in its natural fiate, that ts^ ihewcd no 
figns of being electrified; therefore 
the rod was only (at this time) inlu* 
entially cledirified. 

A.M. 

A.M. P.M. a fhower of rain ; theelcc- 
tricity became negative. 

In the forenoon, P.M. a ftrong gale 
of wind. I now faw thunder clouds 
forming at a great height. Half aftci: 



Sept. 



relating to jttmojj^herk EkSricity, 



»99 



Days. 



Wind 



JBa 



rom. 



Ther. Sparks. Pof. Neg 



Inches. 



Sept. 4 



8 
9 

lO 

II 

12 

^3 
i6 



SE 

SW 

SW 

SW 

SW 
SW 
SW 
N 

N 
W 
SW 

w 

SW 



29.50 

^9-95 
30* 3 

3015 

30.15 
30.12 

29-95 
30.10 

30.10 

29.85 

29.82 

29.74 



68 
69 

59 
62 

67 
68 
68 
61 

54 

54 

60 

48 
48 



iinall 
fmaU 



fmall 



o 
o 
o 
o 
o 
o 
o 
o 
flrong 



neg. 



ncg. 



pof. 
pof. 



pof. 



neg. 



five o'clock appearances were dread- 
ful ; in five minutes time the (Irong 
gale of wind became a ftbrm from 
SE.. This ftorm of wind, (for there 
was but little rain) carried the huge 
black clouds to the N\V, for there I 
faw abundance of red lightning a little 
above the horizon, and 1 once heard a 
rumbling of thunder. The rod be 
fore the ilorm was- poiitive, but by it 
was changed to negative, and conti 
nucd fo during the whole time. The 
electricity of the rod often varied in 
flrengtb, fomctimes weak, fometimcs. 
llrong, without cliange of kind. At 
Ameriham, in Berkfliire, and at the 
fame time at the Earl of Aylesford's 
park, near Fackington, in Warwick- 
ill ire, was a mod tremendous florm 
of hail, rain, lightning, and thunder, 
from 4 to 6 o'clock P.M. 

P.M. There were four gradual changes 
of the elcdricity in two hours.. 

P.M.. There, haa been a little rain to- 
day. 

P.M. and near fun-fetting negative; 
there was fome fmall rain. 

A.M. by the night bottle; that in the 
rod very weak. 



, Only, weak figns of clcdlricityj 
not open. 



balls 



By the night bottle» 

} Weak figns ; balls not open. A dark 
atmofphere. | 

A.M. There were feyeral heavy clouds 
pafled from the SW^by which the rod 
was highly charged with pofitive eledri- 
city.The bell rang briikly. This charge 
laftcd from a litt le before eleven o'clock 

Sept^ 



iOD 



M-. Rbad^s Metiorologtcal y^tmai 



Days. 


Wind. 


Barom. Ther. Sparks. 


Pof. jNcg. 


1 






Inche*. 


« 








A.M. to full Gx o'clock P.M. during 
which time there were four gradual' 
changes of the eledtricity. 


Sept. 17 NW 


29.92 


44 





_ 


neg. 


By the night bottle. 


18 NW 


29.61 


S* 





— 


neg. 


A.M. a more tranGent viGt of the elec- 
















tric fluid I never before faw, juft while 
















a fmall black cloud pafled over the 
















rod, and let fall a few drops of rain ;| 
















the whole time of the charge was 
















about 4 minutes. 


19 


-^W 


29,40 


48 





— 


ncg« 


A.M. by the night bottle. The elec- 
triGcation of the rod very weak. 


20 W 


29.40 


60 





— 


— • 


Weak Ggns ; balls not open. 


21 W 


29.40 


60 


&m11 


— " 


neg. 


A.M. by the night bottle. P.M. the 
rod wat ele£triGed negatively. 


22 NW 


30- 9 


S« 





— 


neg. 


By the night bottle, aod the rod alfo. 


23 NW 


30. 2 


SI 





— 


neg. 


« 


a4 


NW 


30-a3 


61 





— 


neg. 


1 


\i 


NW 

S 
SW 


30.26 
30.26 


49 






— 


neg. 


1 The ele6bical charge hat been very 


49 
61 




neg. 


^ weak thefe eight days, only juftfu^ 


27 


30- 





^■" 


neg. 


1 ficient to indicate the kind. 


28 


W 


30- 


S» 





— 


neg. 




29 


S 


29.71 


^l 





— - 


neg. 


1 


30 


s 


29. I 


48 





_. 


neg. 


y 


oa. I 


SW 


29.22 


53 


finaU 


pof. 


"■■■ 


A.M. by the night bottle, wlechwas 
fufficiently charged to give a bright 










' 1 




fpark on making the circuic. At noon 
















feme rain fell, by which the nxl be- 
















cane eledriied negatively, aftd vezy 
















firong, which lafied full four hours j 
















during that thoe, the elearicif^ 
















changed four tiafs, w4iich wereal 
















gradual. 


a 


SW 


29.28 


47 


flrong 




nflg. 


A.M. P.M. tfat sod wat elearified 
po&thrdy, and afterward* negfltivelyj 
with ftrongfparka at the braia ball L. 


3 


SW 


29.11 


48 


Saong 


pM« 




A.M. but «iuch iDMe Wrongly pofitive 
m the afternoon ; thp bell for a ihortt 
time Tang briiUy^ after that ftintly, 
then Sopped, and the ele&ricity 
changed to negative, , which continued 
fome honrs, then declined gradually to 












1 


MHM 


weak fignt only. 1 



oa. 



relatlf^ to AtmeJ^heric EkSrieity, 



201 



Days. 


Wind. 


1 
Barotn. Ther. 


Sparks. 


1 

Pof. Ncg. 




oa. 4 




Inches. 













W 


29.40 


5» 





pof. 


•— 


A.M. by the night bottle. 


i 


S 


2953 


45 


fmall 


pof. 


— 


A.M. And P.M. negative. 


S 


29.50 


56 


imall 


pof. 


— 


A.M. P.M. the fame, but much ftronger. 
















There hath been to-day a cold fmall rain. 
















The ele^icity changed four times in 
















two hours. This day, at Whitehaven 
















and Lancafter, was much lightning 


. 














and thunder, rain, hail, Sec. 


7 


W 


29.27 


45 


fmall 


pof. 


■"^ 


A.M.; but in the aftemfoon a much 
flronger po&tive charge. 


8 


£ 


29.20 


48 





pof. 


— 


A.M. 


9 


SW 


29.29 


46 





pof. 


— 


A.M. 


10 


SE 


29.50 
29.80 


45 





pof. 


— 


A.M. 


II 


S£ 


49 





pof. 


— 


A.M. 


12 


S 


29.46 


53 





— 


— 


'^ 


«3 


N 


29.50 


5^ 





—^ 


— 


Weak figns ; balls not open. Dark, 


H 


W 


29.50 


^} 





— 


— . 


hazy weather. 


*5 


W 


29.52 


56 





— 


— 




i6 


w 


29.67 


42 ' 


fmall 


pof. 


■■"• 


A.M. juft fufficient to emit viiible 
fparks. 


«7 


w 


29.90 


Afi 





pof. 


— 


P.M. by means of a fog. 


i8 


s 


29.67 


5* 





— 


ncg. 


P.M. balls open fix-tenths of an inch. 


19 
so 


s 

SW 


29.79 
a9-7S 


58 i 







..^ 


■^^ 


i Weak figus ; balls not open. 


21 


s 


29.89 


53 I 


C 


pof. 




A.M. 


22 


w 


3°' 4 


50 





— 


— 


•) 


as 


NB 


30. 7 


55 

47 





— 


•— 


/ 


»4 


£ 

N£ 
£ 


30-34 
30.28 

, 30*7 








z 


E 


Weak figns of clcaricity; balls not 
; open. Dark, hazy weather, and 

moift air. 


^S 


£ 


30.27 


45 





*— 


-^' 




£ 


30.30 


40 





— 


... 


, 


29 


N 


30.13 


46 





— 


— 


J 


3° 


E 


30- 3 


40 





pof. 


— 


P.M. by means of a little cold rain. 


3» 


N 


29.92 


♦2 





pof. 


— 


P.M. a viery high north wind. 


Nov. I 


N 


30.32 


3! 





— 


— 


\ 


a 


N 
S 


29.59 


46 





— 


•"- 


1 Only weak figns of the eledric fluid ; 


3 


29.19 


^ 





*"" 


^^" 


> balls not open. A dark, clouded 


4 


SE 


29- 3 







■"• 


atmofphere. 


5 


S 


29.29 


50 





,^^ 


•^— ' 




6 


W 


28.82 


48 





"■" 


■^ 





Vol. LXXXI. 



£e 



Nov, 



202 



Mr. Read's Meteorological Journal 



Day«, 


Wind. ' 

1 


B.irom. 


1 
Thcr. Sparks. 1 Pof. 


Ncg. 


^ 






Inches. 







I 






Nov. 7 


w. 


28.90 


43 


fmall 




neg. 


A.M. by a fliower of fleet, which for a 
ftiort time occafioncd the rod to emit 
bright Ipaiks at the ball L. 


8 
9 


NW 
W 


29. 9 
29.29 


40 
30 






"■"" 


neg. 
neg. 


A.M. by the night bottle. 


lO 


w 


29.90 


37 


fmail 


pof. 


— 


A.M. by means of a fog. 


II 


w 


2993 


39 


fmall 


— 


neg. 


A.M. 


12 


sw 


29.70 


45 





pof. 




P.M. This was obtained in the following 
manner. Soon after funfet I per- 
ceived a light-coloured dewy vapour 
arife 20 or 30 inches above the ground 
in the park ; the evening being ferene 
and fair, I flood upon an infulated 
ftuol, and waved my exploring rod 
among the dew *, and with my finger 
touched a fenfible elearometer, which 
inftantly opened with pofitive eledri- 
city. As the evening advanced, a 
ftrong fog filled the air ; when it. was 
of fufficient height for the high or fixed 
rod, this alfo became electrified with 
the fame kind of eledricity which I had 
received near the earth's furface. 


13 

• »4 


w 

sw 


29-73 
29.63 


40 
46 






~~" 





• Weak figni only ; balls not open. 


IS 


sw 


29.42 


47 





— ~ * 


— 


Notwithdanding all my care and atten- 
tion to my pointed rod, this day it 
















has been intirely fniftrated ; for I have 
not perceived any figns of the ele<ftric 
fluid. However, it is the firfl day it 
has wholly failed me, A moid air 



* When I find that the moiftupe 10 the air has fo far injured the infutation of 
my high>pointed rod, that it will not retain the eleftric fluid ; in that cafe, I 
make ufe of a fmall. cod. which' I hold in my hand, and projed through an upper 
window ;. having firfl nuarmed the ftool legs^ I place myfelf upon it, &c. I find 
this method to be a good fubflitute in damp weather. The rod is about the 
kogthi and. (tiength of a fifliing-rodi with plenty o£ fmall wire twined round it. 



Nqk;. 



relating to Almofphtnc EUdliicity, 



203 



Dayj. 



Nov. 16 
»7 

18 
»9 

20 
21 



22 
23 

»4 

2< 

27 

28 
29 



Wind. 'Barom, 



30 

Dec. I 

a 
3 



SW 

s 

s 
s 
w 

NW 

N 

ME 

NE 

N 

N 

SE 

W 
NW 



SE 
6 
S 



Inchei. 



29-43 
29.54 

29.51 
29.69 
29.65 
29.86 

29.89 
30.12 

30.29 

30.20 
30.30 

30.45 

30-43 
.30'30 



Ther.'Sparkj, Pof, Ncg. 



30.10 

29.71 

29-75 
29.90 



43 
47 

40 
43 
47 
44 

44 
42 

41 

37 
37 

30 

33 
35 



38 

38 
50 
39 



o 
fmall 

o 
o 
o 
o 

o 
o 

fmall 

o 

fmall 



o 
finall 



o 

o 

firong 



— neg. 



I pof. 
pof. 
pof. 



pof. 

pof. 
pof. 



I] 



has prevailed for many days ; nnd 
there have been fix lioiir» drizzling raia 
to-day» which mufti. fTcn the exnt'tneU 
of rhe infiilntion of the rod, and airalloj 
Weak figns ; balls not open. | 

A.M. fmall fparks were in the rod, the 
greatell part of this day. 



A.M. by means of a fog. 



pof. 
pof. 



pof. 



pof. 
pofi 



ncg. 



A.M. by the night bottle, which I 

I found well charged. 

.Weak figns only. 

jNo figns. This is the fecond failure. 
A moift atmofphere. 

'a fog. There were vifible fparks during 

I the greateft part of the day. 

A.M. by means of a fog. 

AM. and P.M. poiitive, with line 
fparks. 

At break of day. Afterwards pofitive, 
by means of a fog. 

All day, by a continued fog. 

All day. The fog ftill continues. 
have obfcrved, during thefe three days 
and three nights (abating a little time 
for flcep, and which I curtailed for fo 
noble a purpofe), that a foggy va- 
pour was conftantly ele£trified pofi 
tively. The pith balls diverged from 
a quarter to three quarters of an inch, 
except when the fog (which was gene 
rally moderate) fuddenly becsrme thick 
and dark ; then the balls would open 
to near two inches ; at thofc times I 
received the electric fluid into bottles 
This fog began firongly negative. 

INcarly all day. The fog is entirely 

I gone. 

jWeak figns ; balls not open. 

P.M. A moifi air to-day. 

'AU day (I mean 16 hounoutof 24), 

I the weather foggy. 



£e2 



Dec. 



204 



Mr. Read's Meteorological Journal 



Days. 


Winds. 1 


Barom. 

1 


Thcr. 


Sparks. iPof. Neg. 


1 






Inches. 











Dec. 4 
5 


S 
SW 


30.10 
30-38 


43 
52 






— 


[ Weak figns j balls not open. 


6 


SW 


30.40 


48 





— 


— 


No figns of clcftricity. The thirc 
failure. A very moift air. 


7 


SW 


30-49 


42 





pof. 


— 


A.M. a (light fog. 


8 


SW 


30-54 


40 


fmall 


pof. 


— 


P.M. 


9 


'SW 


30-55 


34 





poi. 


— 


A.M. 


lO 


w 


30.52 


39 





— 


— 


Weak figns ; balls not open. 


11 


SW 


30-54 


4« 





pof. 


— 


1 A.M. and P.M. The weather fercnc 
and fair. 


12 


SW 


30.41 


44 





pof. 


— 


13 


SW 


30.30 


47 





— 


— 


Weak figns. 


»4 


s 


2992 


44 





— 


neg. 


A.M. from a little rain. 


«5 


SW 


28.95 


45 





— 


— 


No figns of ckdricicy. The fourth 
















day's failure. 


16 


SW 


29.40 


40 


flrong 


pof. 


— 


P.M. a Ihort (hower of fnow, by which 
the rod was (Irongly electrified. ^ 


17 


w 


29»5 


38 





— 


— 


No figns of eledricity^ The fifth day's 
failure. 


18 


w 


3°- „ 


50 


fmall 


pof. 


— 


A.M. a finefcrene morning. 


, *9 


SW 


29.58 


44 







neg. 


P.M. by a fmall rain. On an incrcafc 
















of the fall of rain, the electricity 
changed to pofitive. 


20 


SW 


29.72 


44 


O' 


— " 


i— 


Weak figns. 


21 


SW 


29.78 


45 





-— 


-^ No figns of ole^trkity^ The Cxth day's] 
















failure. A very damp air. 


22 


SW 


29.60 


S6 


. 


— 


— 


No figns. The feventh day's failure. 
















A moift air. • 


n 


w 


29.7S 


49 





— 


— 


Weak figns of electricity. 


»4 


w 


29.27 


52 


fmall 


- Beg. 


At eight o'clodk. A.M. began a fmall 
















.fliower of rain, which was weakly 




*» 










. 


. electrified negatively ; ps the fall of rain 
increafod, fo 'did theiintenfity of the 
electric fluid increafe with it, and after 
continuing for two hours, they both 

} difappeared together. , 


25 


SW 


29.41 


■42 


ftrong 


— ncg. 


A.M. by a fliower of ra;n. Ten o'clock 
















' P.M. a fog (Irongly eleCtrtfed pofitive. 


26 


W 


29.89 


46 


fmall 


pof. 


_ A.M. I 


27 


SW 


29.80 


46 





«- 




Weak figns, . . 


28 


w 


29.88 


47 





pof. 


* 


P.M. from a very (hm fog: 


29 


SW 


29.75 


54 





■ — '* 





1 


30 


SW 


29.76 


42 










yOnly weak figns of cleCtricityv 


„ ?^ 


& 


a9-73 


48 







, 


J _ 



Jan. 



relating to Almofpheric Ek&rlcliy, 



105 



DajTi. 


Wind. 


1 
Baroro. Thcr. 


Sparks. ' Polf. 


Ncg. 




i 1790 




Inchei. , 










Jtn. I 


SW 


29-90 35 





pof. 


— 


Both A.M/aud P.M. pofitive. 


2 


S 


30.30 36 


fmall 


pof. 


— 


All day. 


3 


S 


29.98 : 46 





pof. 


— 


AH the day, by a fog. 


4 


W 


30.20 43 


fmalt 


pof. 


— 


All the day, and bright fparks fevcral 
















tinnes to-day. 


5 


N 


30.25 


45 


fitiall 


pof. 


— 


All the day, with fine fparks. 


6 


SE 


30.19 


41 





pof. 


— 


A.M. 


7 


W 


30.40 


41 


fmall 


pof. 


^^ 


A.M. weather dry and ^0%^. 


8 


w 


30-45 


36 


fmall 


pof. 


^^ 


Nearly all day in charge. 


9 


' E, 


30.28 


36 





pof. 


— 


A.M. bails open near one inch. 


10 


SE 


30.24 


39 





pof. 


— 


A.M. and P.M. 


II 


S 


30.11 


41 





pof. 


*-, 


P.M. 


12 


W 


30.20 


45 





— 


— 


Weak figns. ' 


>3 


SW 


30-34 


42 





pof. 


— 


A.M. 


15 


S 


29.95 


49 


finall 


-« 


ncg. 


A.M. a fmall rain, by which the rod 














was eledtrified negatively. 


NW 


29.91 


43 





pof 


— 


A.M. 


16 


SW 


»9-95 


42 


fmall 


pof. 


— 


A.M. weather very mild and fair. 


, 17 


N 


30.28I 40 


p 


pof. 


— AM. 1 


18 


NE 


30.20 39 





pof. 


— . 


A.M.andPaM. 


»9 


£ 


30-'3' 33 





pof. 


— 


A.M. and P.M. 


20 


SE 


30.24, 32 


fmall 


pof. 


— . 


A.M. 


21 


E 


30.40, 3» 


fmall 


pof. 


— 


A.M. and P.M. 


22 


W 


30.38 


35 


fmall 


poC 




All the day, from a fog. The ftrength 
of the eledtric charge in the rod was 
much governed by the occalional in- 
tenfity of the fog ; for as one abated 
in ftrength fo did the other, and the 
contrary. At ten o'clock P.M. I re- 
ceived bright fparks at the ball L. 


23 


W 


30-33 


40 


fmall 


pof. 




Seven o'clock A..M. I found the rod 
cleifVrificd, fufficiently ftrong to emit 
yifible fparks, and often afterwards 
the fame day. 


24 


W 


30.16 


46 


fmall 


pof. 


— |a-m. ^ 1 


25 


NE 


30.11 


42 


fmall 




neg* jThcre wa* a moderate (howcr of rain| 


«# 














this morning, by which the rod was. 
















cle£trified negatively. 


26 


W 


30. 2 


40 





pof. 


— 


1 A.M. balls open from two to feven 
J tenths of an inch. 


^2 


w 


29.30 


42 





pof, 


^. 


s 


29.50 


44 


fmall 


pof. 


— 


A.M. at noon fell a fmall rain, which 


_ 




* •J 










1 was yoid pf eleftricity. Near ten 



Jan. 



2C6 



Mr. Read's Meteorological Journal 



Days. !\V>n<'*- .'Barom. 



Jai>. 29 



Feb. 



30| 

, i! 

2 
3' 

6' 

I' 

9 
10 

II 

12 

»3 

14 
»S 
16 



»9 
20 

21 

22 
23 
44 
25 
26 



w 



N 
S 
N 
SW 
W 
W 
SW 

w 

NW 
N 

w 

NE 
W 

w 

SW 

SW 

w 

s 



w 
w 

s 

SE 
SW 
SW 

s 

SW 

s 

W 



Inches, 



29.26 



29.50 
29.68 
29.87 
30.10 

30-3° 
30.60 

30.61 

30.63 

30.35 
30.22 

30- 5 
30- 7 
30.20 
30.20 

30.34 

30- «5 
30.22 

29.95 



30.20 
30.42 
30.48 
30.42 
30.38 

30.43 
29.97 

30. «S 

2999 
29,88 



Ther 



40 



41 
46 
40 
40 
44 
46 

43 

44 
39 
36 
40 
43 
41 
45 
4a 

44 
40 

44 



39 

42 
45 
40 

42 

:i 

44 
S« 
51 



Sparks. Pof. Ncg. 



O 
o 
o 
o 
o 
o 
o 
o 
o 
o 

fmall 
o 
o 
o 

fmaii 

o 
o 
o 



o 
o 
o 

fmall 
o 
o 
o 

* o 
o 
o 



pof. 



pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 

pof. 
pof. 
pof. 



pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 
pof. 



ten o*c1ock P.M. a fuddea iho^er of 

rain, ftrongly negative. 
P.M. A delightful clear fine day, but 

the atmofphcric electricity was very 

weak till night came on. 
A.M. And P.M. negative. 



Balls open from one to nine tenths 
of an inch, weather fair and fe 
rene. 



Sparks juft vifible. 

V Serene weather dill continues. 

Nearly all the day, with fine bright 
fparks. 

} Balls open from two to fix teaths of 
an inch. 

A.M. A fmall rain P.M. which did no^ 
occafion any change in the eledb-ic 
fluid. 

} Balls open half an inch, weather fiill 
ferene. 

A.M. A foggy day. 



} 



Balls open from one to nine tenths 
of an inch, weather Ml mild. 



P.M. I have often obferved that impe* 
tuous winds leifen the intenfity of at 
mofpheric ele^ricity in clear weather, 
which has been verified thisday ; fprnot 
the leaft fign of electricity cot^d be ob* 
tained from the rod till after fnoiety 
at which time the high weft wind hav-- 



F«b. 



relating to AtmoJ^hertc EkSlricity. 



207 



Day, 


Winds, ' 


Barom, Ther. 


Sparks. 


Pof. Ncg. 








Incbei. 











ingfubfidcd, a little low vapour fprung 
up ; I then received the fluid in great 
plenty, and of the fame kind that it 
has continued to be for twcnty-fcvcn 
dayspafb. 


Feb. 27 
28 


W 

NW 


30.20 
30.22 


4* 
45 






•» 


..^ 


Weak figns : balls not open. 


Mar. i 


N 


30*3* 


47 





pof. 


— 


A.M. 


2 


NW 


30.49 


SO 


finall 


pof. 


— 


A.M. fparksjuftvifible. 


3 


N 


30-33 


49 





pof. 


— 


1 


4 


NW 


30.27 


40 





pof. 


*— 




5 


NE 


30.3* 


43 





poC 


— 


>Vcry mild ferenc weather. 


6 


NW 


30.47 


40 





pof. 


— 




7 


NW 


30.4s 


4a 





pof. 


— 


/ 


8 


SW 


30«44 


4* 


finall 


pof. 


■"" 


A.M. vifible fparks. Still no change 
of kind. 


9 


SW 


30.20 


4» 





pof. 


— 


A.M. 


10 


SW 


29.90 


46 





pof. 




P.M. A ftrong gale of wind, to-day. 
The atnaofpherc is extremely dry. The 
fun appeared bright all day. No at- 
noofpheric elc^ricity could be obtained 
till near ten o'clock at night. This 
















day, at Hallifaz, fell a fhower of fnow, 
accompanied with one flafh of light- 
ning and one clap of thunder. 


II 
12 


SW 
S 


30.20 
30.31 


4« 

SI 






pof. 
pof. 


•^ 


A.M. Still moderate weather. 


»3 


SW 


30.20 


4» 





pof. 




A.M. Nine o'clock PM. to eleven 
o'clock there was a moderate (hower 
of rain, which was eleftrified nega- 
tively. I have not till this perceived a 
negative charge fince January the 28th. 


»4 


NW 


30.50 


49 





pof. 


■■■' 


A.M. At Thurfo, in Scotland, hail, 
lightning, and thunder. 


»5 


N 


30-57 


S« 





pof. 


• ^^ 


P.M. 


16 


N 


30.60 


40 


fmall 


pof. 


— 


A.M. vifible fparks. 


17 


NE 


30.60 


40 





pof. 


— 


^ 


18 


NE 


3050 


45 





pof. 


— 


• A.M. a very dry atmofpherc 


19 


£ 


3055 


44 





pof. 


— • 


J 


20 


£ 


30.44 


43. 





pof. 


■■" 


A.M. there was an hoar froil upon the 
grafs this morning. 


21 


' B 


30.39 44 





pof.' -- 


A.M. 



Mar. 



20S 



Mr, Read's MeteorokpcMt Journal 



Days. 


Wind. 


Barom. 


Ther 


Sparks. 


t 

Vo^, Ncg. 






Inches. 













Mar. 22 


E 


30- '5 


42 





pof. 


— 


•V 


23 


sw 


29.81 


46 





pof. ' 




24 

25 


S 


29.80 


51 





pof. — 


^A.M. divergency of the pith balls 












from one to nine tenths of an inch. 


NW 


3°- 


46 





pof. 




26 


E 


30- 4 


48 





pof, _ 


J 


27 


£ 


3P- 


46 





— neg. 


A.M. from a fmall ftiower of rain. P.M. 




» 












the fluid was pofitivc. 


28 


NE 


29.98 


44 





pof. 


-^ 


P.M. 


29 


N 


3°- 


48 





poC 


— 


P.M. the air a little foggy. 


30 


£ 


29-95 


44 





po£ 


""" 


A.M. not a beam of fun has appeared 
this day. 


3> 


E 


29-93 


47 





pof. 


— 


A.M. balls half an inch open. 


April I 


E 


30- 5 


45 





pof. 


— 


A.M. 


2 


£ 


30.20 


41 


fmall 


pof. 


— 


A.M. vifible fparks. 


3 


E 


30-25 


40 





pof. 


— 


•^ 


4 


E 


30.19 


40 





pof. 


— 


Balls open from one to feven tenths 


5 


NE 


30.23 


47 





pof, — 1 


of an inch. 


6 


E 


29-95 


36 





pof. 




' 'Weak figns of elearicity. This weak 
ilate has not happened fince the 31ft 


7 


£ 


29-75 


45 





— 


— 


of December. There has been for 


8 


£ 


29.75 


52 









A many days a ftrong eafl dry wind, 
which feems hitherto nearly void of 
the eiediric fluid. 


9 


£ 


29-57 


66 


fmall 


— neg. P.M. from a fine fiiower of rain. | 


10 


£ 


29.50 


40 


fmall 


— ncg. 


A.M. the rain continues, fo does its 
















negative electricity. 


II 


£ 


29.36 


35 


fmall 


pof. 




A.M. from a little fall of fnow. P.M. 
fome fnow mixed with rain, on which 
the rod became charged much more 
flrongly pofitivc. The rod has been 
charged full four hours to-day. 


12 


E 


29-35 


39 





_ 


— 


Weak figns ; balls not open. 


»3 


E 


29.70 


38 


fmail 




neg. 


A.M. a nwdcratc rain, but ftrongly 
elearified, and continued fo full two 
hours. There were two gradual 
changes of ele&ricity. 


14 


NE 


29.81 


41 





~ ncg. 


P.M. but after funfet the rod was elec- 
trified pofitively. 


IS 


E 


29.&8 


35 


fmall 


— jncg. 


Six o'clock A.M. a little rain fell. Half 












1 1 


after eight o'clock, a fine fliowcr of 



April 



rtktif^ to Atn^/piferic EkSnc^y, 



i»99 



Dajrt. 


Wind. 


Barom. 


rher. 


Sparks. 


1 
Pof. Ne«, 








Inches. 





i 






fnow; the rod now became firongly 
eledrified pofitively. Denfe fparks 
were now received at the ball L ; half 
after nine o'clock, the cle£kricity 
changed to negative. I caught fome 
of the fn^Dw in the apparatus men- 
tioned the 20th of July in this journal, 
and I found it weakly eledrified. 


April 1 6 


NE 


29.8« 
29.98 


4» 





pof. 


— 


"\ 


'7 


N 


42 





pof. 


— 


/ 


18 


NE 


29.80 
29.69 
30.26 


40 





pof. 


— 


/ Divergency of the pith balls was 


19 


NE 


4» 





pof. 


■"" 


e from a tenth to fevcn-tenthi of an 


20 


SE 


45 





pof. 


■"" 


inch. Fine ferene weather. 


21 


S 


30.23 


47 





pof. 


"■" 




22 


S 


29.94 


5» 





pof. 


— * 




23 


SW 


29.70 


55 





poC 


— 


^ 


24 


W 


29-55 


52 





pof. 


""■ 


A M. and P.M. negative from a little 
fall of rain. 


25 


SW 


29.60 


5» 


ftrong 


pof. 




Half pad nine o'clock A.M. ' A diftina 
black cloud approached the rod, and 
fome heavy drops of rain fell; the 
















elc^ricity of the rod then changed to 
negative. About half paft three 
o'clock P.M. a very large low cloud 
paiTedover the rod, and" rained alitde, 
on which the rod became ftrongly elec- 
trified pofitively. 1 


26 


NE 


29.85 


53 


fmall 


pof. 


— 


A.M. P.M. on the fall of (bmc rain, 
the rod was charged negatively. 


^S 


N 


29.98 


47 





pof* 


— 


The divergency of the balls from two 


W 


29.80 


50 





pof. 


"■^ 


I to fix tenths of an inch. Serene fine 


29 




29.69 


5» 





pof. 


— 


weather. 


30 




29.58 


53 





pof. 


— 


J , 


May 1 


£ 


29-75 


50 


fmall 


pof. 




Nine o'clock A.M. a (bower of ram ; 
the eleAricity now became negative. 
The rod has been elearified to-day 
from fix o'clock A.M. to ten o'clock 
P.M. and I fuppofe all night alfo. 


2 


N 


30.22 


41 





pof. 


— — 


1 Divergency of the pith balls from 
J three to feven tenths of an inch. 


3 


NE 


29.85 


49 





pof. 


— 


4 


SE 


29.63 1 51 


fmaU 


pof. 


""• 


A.M. 



Vol. LXXXL 



F f 



May 



2:to 



Mr. Re AD*s Meteoroh^ical Joumat 



Days. 


Wind. 


Baroro. 


Ther. 

e 


Sparks. 


Pof. 


Ncg 








Inches. 










May 5 


S 


29-73 


52 


ftrong 


pof. 




Six o'clock, A.M. vtvy cloudy. Eighr 
o'clock it rained, the cleftricity now 
became ftrongly neg-ative, with fine 
fpaiks at the ball L. This fhowcr 
having ccafed, another foon followed, 
which elcdrified the rod pofitivcly. 
I'he rod was charged 7 hours to-tlay. 


6 


SW 


29-75 


50 


fmall 




neg. 


Every appearance at the rod to-day was 

neaily as during the preceding one. 

Balls open from one to five tenths 

of an inch. Such weak figns of elec* 

tricity, as have been obfenred for 

thcfe two days, are thq ufual efl&'^ts 


7 


W 


30.10 


56 





pof. 


— 


^ of a very ftrong and dry wcfterly 


8 


■w 


29.84 


50 





pof. 




1 wind i and in general, let a ftrong dry 
I wind blow from what point of the 
1 compafs it may, it is attended with 














t weak figns of eleftricity* 



The above-mentioned eighth day of May completes this jour- 
nal of one whole year, which I give to the curious in atmo- 
fpheric eledlricity as a faithful narrative of fads, having never 
once deputed another perfon to make obfervations for me. 

JOHN READ, 

of Knightibridgei near London^ 



A monthly 



nlating to Almofpberic Eie^ricitj^ 



2ir 



A monthly account of ele£l:rical fparks, and of politive and 
negative eledricity, as indicated by the pith-ball ele£tro* 
' meter, and fometimes by only flaxen threads without balls 
to them. 



23 days of May, 1789, 
8 dayi of May, 1790, 
June 
July 
Auguft 
September 
Odober 
November 
December 
January 
February 
March 
April 









Number of dayt in each 








month in which fparkt 








were perceived. 


Timet. 


Timet. 


Dayt. 


PoCtive 


»7 


Negative 


18 


9 


Pofitivc 


3* 


Negative 


3^ 


la 


Pofitive 


13 


Negative 


aa 


12 


Pofitive 


19 


Negative 


19 


9 


Pofitive 


9 


Negative 


as 


7 


Pofitive 


17 


Negative 


7 


7 


Pofitive 


la 


Negative 


8 


8 


Pofitive 


la 


Negative 


6 


7 


Pofitive 


26 


Negative 


4 


'3 


Pofitivc 


a6 


Negative 





3 


Pofitive 


30 


Negative 


I 


3 


Pofitive 


a8 


Negative 


la 


8 



a4i 



156 98 



It appears from this journal, that there were onlyjeven days 
throughout the year in which no figns of ele£tricity were per* 
ceived; viz. the 15th and 23d of November, and the dth, 
i5thy lythf aifty and 2 2d of December. 



Remarks on the phaenomena exhibited by the rod on the 

31ft of Auguft. 

I was for a long time extremely puzzled to account for the 
rapid changes which the pith balls on fome days fo frequently 

F f 2 cxhi- 



2ii . Mr. RfiAD*aJ Meteorahgkal Jonmali &c. 

exhibited; being pofitive one minute, then negative for ano-. 
ther, and the next returning- again to pofitive. From oftea 
cowfidering this apparently whimfical changeablenefs in nature, 
I was at length induced to fufpeft, what indeed was after- 
wards confirmed by aftual experiment, viz. that fome of tbefe 
changes are only apparent, and not real, they being occafioned 
not by the a£lual communication of a different fort of eleSri- 
city, but merely by the aftion of eledtrical atmofpheres ; thus, 
when an eleflrified cloud comes within a certain diftaiice of 
the rod, and before it comes near enough to impart t6 it fbme 
of its own elcftricity, the eledlrrcal afmofphere of the former, 
agreeable to the well known laws of eleftricity, will difturb 
the eleftric fluid naturally belonging to the rod, and will con- 
fequently occafion feveral apparent changes in the electrometer, 
^hich changes an unexperienced ebferver wouM attribute in- 
tirely to, the change of eleftricity in the clouds. 

This obfervation was evidently confirmed by the phaenomena 
obferved on the 31ft of Auguft ; and thence it appears, that 
the real number of changes from pofitive to negative, or from 
negative to pofitive electricity, cannot be fb great as it is ihewn 
by the electrometer affixed to the rod. 

I cannot help lamenting with Stgnor Beccaria, that there 
are fo few high pointed rods ereCled to afcertain the eledlrical 
flate of the earth and atmofphere at all times ; but more par- 
ticularly during thunder ftorms. If there had been pointed 
rods, for infltance, at Whitehaven and Lancafter on the 6th of 
October, and well attended to at the time of the ftorm. of 
lightning and thunder, which happened at both places nearly 
at the fame time, it would then have been known, whether 
the apparatus might not be pofitive at one place when it is 
negative at the other. 



Fhavs.Thin4. Vol. LgPLl. Thh, V, p.M. 




[ "3 ] 



XIII. Farther Experiments relating to the Decompojition of 
dephlogifticated and inflammable Air. By Jofeph Prieftley, 
LL.D. F. R. S. 



Read April 7, 1791. 

TH E doftrine of pbhgt/ion^ and that of the decompofition 
of water^ have long engaged the attention of philo- 
fophica) chenoifls, and experiments have fonf>etimes Teemed to 
favour one conclufion^ and fometimes an oppofite one. I have 
myfclf been very differently inclined at different times, as ap- 
pears in my publications on the fubie£t ; and I am hardly fen- 
fible of a wi(h which way this ino^portant controverfyi as it 
may be called, be decided, notwithffandicg the part that I have 
taken in it. I. cannot help thinking, however, that the expe- 
riofienls., an accoit^ntf of which I (ball now lay before the So* 
ciety, are decifive in favour of the compofition of an acid from 
depblogifticated and inflammable air ; and, therefore, that the 
opinion of thefe two kinds of air neceffarily compofing water 
cannot be well founded. It is, indeed, fufficiently evident, 
that the fame elements likewife compofe^;i;^^ air^ and there- 
Ibre it is the lefs extraordinary that they fliould compofe ano- 
ther acidw 

The doctrine of phlogifton I would, however, obferve, will 
not be affefted by the moft decifive proof of the compofition 
a£ water from dephlogifticated and ififlamouible air ; iince this 

would 



ii4 JDr. Priestley*s Experiments relating to the 
would only prove^ that phlogidou is one conftitucnt part of 
water ; which is an opinion that I have advanced, and men* 
tioned on feveral occafions ; and it is the lefs extraordinary, as 
water refembles metals in the remarkable property of being a 
pretty good conduftor of eledricity. What I (hall now allege, 
however, will make it very doubtful, whether pure water be 
ever formed by the union of dephlogifticated and inflammable 
air; and perhaps make.it more probable, that water, as 1 have 
lately advanced, is only the bafis of thofe kinds of air, as well 
as of every other kind. 

It was objededtomy former experiments on the decom por- 
tion of dephlogifticated and inflammable air, by firing them toge-> 
ther in a copper veflel, which always produced an acid liquor, 
that this acid came from \ht phlogifticated air with which the de* 
phlogiflicated air that I made ufe of was necelTarily more or 
lefs diluted ; or from that which I could not wholly exclude, 
as a part of atmofpherical air, when I exhau(led the copper 
veflel by means of an air-pump. 

To obviate this objedlion, I then obferved, that I not only 
conftantly found that the more phlogifticated air was contained 
in the two other kinds of air (mixed in the proportion of two 
meafures of inflammable air to one of dephlogifticated) the lefs 
acid I got ; but that, when I purpofely mixed any given quan* 
tity of phlogifticated air with them, it appeared not to have 
been at all affe£ted by the procefs, but remained the very fame, 
in quantity and quality, as before. Still, however, becauie 
Mr. Cavendish, though in a very different procefs, had 
found nitrous acid to refult from the decompofition of phlo- 
giflicated and dephlogifticated air ; aqd becaufe M. Lavoisier 
and his friends had found nothing but pure water after the 
(low burning of dephlogiflicated and inflammable air ; it was 

maintained 



Decompofitian of depblogi/licated and inflammabU Air. % 1 5 
maintained by the favourers of their fyftcm, that the water 
only in the liquor which I procured came from the union of 
the two kinds of air, and the acid from the pblogijlicated air 
which I had not been able to exclude- 
But let any perfon only confider the very fmall quantity of 
nitrous acid which was procured by Mr. Cavendfsh from the 
certain decompoiition of 319^4 s:rain meafures of atmofpherical 
air, amounting to more than t{ ounce meafures in one cafe, 
and of 2710 grain meafures, amounting to 5I ounce meafures 
in another caie (Phil. Tranf. Vol. LXXVIII. p* 264. 268,.), 
three-fourths of which was phlogifticated air ; and the vadly 
greater quantity which L procured (Ibid. p. 324,), when it 
could not be proved, that a particle of phlogifticated air was 
decompofed, and think whether it was at all probable, that 
the acid came from this kind of air, and not from the union of 
the dephlogifticated and inflammable air, which evidently dif- 
appeared in very great quantities. This circumflance alone 
might have fatisEed thofe who intered themfelves in this quei^ 
tion ; but it does not feem to have been attended to^ 

I have now, however, effedually removed the objedion 
above mentioned, by intirely excluding all phlogifticated air 
from the procef^ ; the dephlogifticated air which I at prefent 
ufe being fb pure,, that it contains no fen fible quantity of phlo- 
gifticated air. I alfo make ufe of no air-pump, but fir ft fill 
the copper veflel with water, and then difplace it by the mixr 
ture of the two kinds of air ; yet, in thefe circumftances, in 
which all phlogifticated air is excluded^ I procure even a 
ftronger acid than before. 

The paper that I fend along 'with this article contains the 
dry refiduum of the turbid green liquor, produced by a fingle 
explofion of a mixture of two parts inflammable and fome- 

thing 



1 16 Dr. Pai ASTLSY*s Experimmti rriaiing to the 

thing more than one part of dephlogifticated ak» in a oo|»per 
veiTel which holds thirty *feveii ouuces .of water ; and a little 
more muft have have remained an the vc^^ which I could 
not get out by draining or ftiaking it. It is moft evident, dierc- 
fore, that the acid necefTary to diflblve fo much copper mud: 
have come from the union of the dephlogifticated and inflam* 
mable air, becaufe there was nothing clfe in the veiieL The 
inflammable air was procured from iron by means of fteam. 

This very pure dephlogiAioated air I firflimagined.couklonly 
be got by the procefs in which I obferved (Experiment6 on Air, 
- Vol. II. p. 1 70.) that I once before procured it, though I then fup- 
pofed the extraordinary refult to be accidental ; becaufe in other 
circumdances I have fometimes had it very pure when I could 
not fucceed in a fecond attempt of the fame kind. It was by 
heating the yellow produdt of the folution of mercury in fpirit 
of nitre, without fuffering the red precipitate into which it is 
converted by heat to come into contact with the external 
air, from which I thought it probable that it might attraA 
fome phlogifton. Afterwards, however, I found that this 
circumflance makes no difference whatever; and that the atr fo 
procured appeared to be purer, arofe from the greater purity of 
the nitrous air which I made ufe of as a teft, and which I got 
from mercury, and not from copper, the nitrous air from 
which I find to be much lefs pure. For trying the dephlo- 
giflicated air yielded by fome red precipitate which had been 
prepared many months by the nitrous air from mercury, it 
appeared to be as pure as that which was procured in the man- 
Her above defcribed. 

That the dephlogifticated air which I now made jxCc of was 

fufficiently pure for my purpofe, appeared from mixing one 

meafure of it with two of nitrous air, whea the wiidle qu(in« 

1 tity 



Decompofition of dephlcgtjiieated and inflammable Air. 117 
tity was reduced to lefs than four hundredth parts of one mea- 
fure; fb that it is probable that, by a more accurate pro* 
portion of the two kinds of air, and greater addrefs in mixing 
them, they might have almoft intirely difappeared. There is 
befidcs fomc reafon to think, from the great variety in nitrous 
air, that the greater part of this very fmall refiduum comes 
from the nitrous air, and not from the dephiogiflicated. 

It will be faid, how is it poflible to reconcile the rcfult of 
this experiment with that of M* Lavoisier and his friends ? 
which I was by no means difpofed to queftion after the publi- 
cation of the ExtraSlfrom the Regifter of the Academy of Sd-- 
ences for Augujl 28, 1790, in the feventh volume of the 
Annates de Cbimie^ in which a diftinfk account is given of a 
large quantity of very pure water procured from the flow com- 
buftion of the two kinds of air above mentioned : for before 
this it was acknowledged, that fome little acid was always 
found in the water fo procured. 

But my late experiments, befides afcertaining the fad of the 
produdion of nitrous acid from the decompofition of dephlo- 
giflicated and inflammable air, throw fome farther light on the 
fubjedl, and may in fome meafure explain their refult ; for I 
am now able to procure, in my own procefs, either nitrous acid 
or pure water, from the fame materials. 

I conftantly obferve, that if there be a furplus of dephlo- 
gifticated air, the refult of the explofion is always the acid , 
liquor ; but that if there be a furplus of inflammable air, the 
refult is fimply water. That phlogiflicated air is not in all cafes 
affefted by this procefs, I completely afcertained, by admitting 
a little common air into that mixtuire of the two kinds of air 
which always produced water, and finding nothing but water 
in the refult. 

VouLXXXL Gg; I find, 



21^ i!)r.' Priest LEY^s Experiments relating to the 

I find, however, that, agreeably to the expferiments of Mr» 
Cavendish, phlogifticated air is decompofed in this jirocefs, 
when there is not enough of inflammable air to fatUrite the 
dcphlogirticatcd air; though when there is a redundancy of 
inflammable air, there is even a produftion of phlogifticated 
air. Putting 0.5 oz. nri. of phldglfticated air to a mixture of 
two ounce meafures of inflammable air and 1.5 02. m. of de* 
phlogifticated air, the whole was reduced by explolioii tb I.05 
oz. m. of the ftandard of i.i, with t\<'o meafurfts of dbphlo- 
gifticated air, which appears by computation to contain no 
more than 0.388 oz. m* of phlogifticated air; fothat oAizot, 
m. had been decompofed in the procefs. When there is a fuffi* 
cient quantity of inflammable air, the phldgifticated air always 
remains unafFefted in this procefs, as appears by mixing any quan- 
tity of it with the two kinds of air to be 'exploded, a'nd finding 
the very fame quantity, as I have repeatedly done, in the itftdunm. 
That when there was a fuflBciency of inflammable ait ifot 
the purpofe, phlogifticated air is even produced in this procefs^ 
was evident from my never teing able td diminiith any quan* 
tity of dephlogifticated air by inflammable air fq far as by good 
nitrous air, and the refiduum alWays containing phldgifticiatcd 
air. Having exploded two meafures of in^ammable ait with 
one of dephlogifticated air, which by a mixture of two mea- 
fures of nitrous air ivas reduced tb 0.04, there ♦vaS & rdfidiTuni 
of 0.1, of tlie ftandard of' 1.3, which appears by cOtfiputatioil 
to contain 0.0767 oz. m. of phlogifticated air. 

The reafon why, in my former experiments, 1 altviyS pro^- 
cured more or lefs acid, rnuft have been t*hat, without any in- 
tention, or fufpefting that any thing depended upon it, I muft 
have had fome furplus of dephlbgifticated air. MjLAVOYsiEk 
I alfo perceive to have taken it for graated^ as I did, thitt 

after 



Decompojttton of dephlogtjikated and infiammahU Air. 2 1 9 
after either of our procefles, any furplus of either of the two 
kinds of air would only have remained unfaturated, and have 
been found unchanged in the refiduum. 

I daim no merit whatever in this obfervation. It was in 
confequence of accidentally finding pure water in what I then 
imagined to be the fame circumftances in which I had always 
before found acid, and which furprized me not a little at the 
time, that I was led to vary the proportions of the two kinds 
of air, till at length I fucceeded in afcertaining the circum- 
ftances on which this remarkable difference in the refult de- 
pends; bnt I am by no means able to aflign any reafon for this 
aiflerence. 

In this ftate of my experiments I concluded, that nitrous 
acid^ though confifling of the fame elements with pure water, 
contains a greater proportion of dephlogifticated air ; and in 
the laft edition of my Objervaiions on Air^ Vol. III. p. 543. I 
obferved, that *• fubftances, poffefTed of very different proper- 
•* ties, may be compofed of the fame elements, in different pro- 
^* portions, and different modes of combination. It cannot 
•• therefore be faid to be abfolutely impodible, but that water 
<< may be compofed of thcfe elements,'* viz. dephlogiflicated 
and inflammable air. 

* ' When J firft prepared an account of my late experiments 
for the Royal Society, I entertained this idea ; but I now con- 
(iderit as at leafl uncertain, • becaufe when I mix the two kinds 
of air in fuch proportions as to produce wafer, I fii^jd in the 
refiduum much more pbhgifiicated air thanl do when acid is 
produced, which afibrds a fufpicion that, in' this cafe, theprin- 
ciple of acidity goes wholly into the phlogifticated air, which, 
as my fbrmer experiments ihew, actually Contains it, though 
it is not cafy toafcertain in what proportion, 

G g 2 Having 



220 Dr. PftiESTLEY^s Experiments relating /o the 

Having exploded three ounce meafures of a mixture of 
Ibmething more than two parts inflammable air, and one of 
dephlogifticated, and another equal quantity in which the in- 
flammable air bore a lefs proportion to the dephlogifticated, * the 
former of which 1 knew would yield water, and the latter 
acid, I found the refiduum of the former to be 0.57 oz. m. 
not afFeded by nitrous air, and weakly inflammable; and ia 
order to find how much phlogifticated air it contained, I mixed 
difi^erent proportions of phlogifticated and inflammable air, and 
concluded, from the manner of fifing ibem^ and this rejiduum^ 
that it could not confift of lefs than one-third of phlogifticated 
air, viz. 0.19 oz. m. But the refiduum of the mixture which 
would have produced acid was 0.62 oz. m. of the ftandard of 
1.0, which I find by computation to contain not more thaa 
0.062 oz. m. of phlogifticated air. I repeated this experiment 
very many times, and never failed to have a fimilar refult ; fo 
that it is very poflible that the pure water we find roay be 
nothing more than the bafis of the two kinds of air; and the 
principle of acidity in the dephlogifticated ^tr, and the phlogiftoa 
in the inflammable air, may combine to form a fuperfluous 
acid in th^ one cafe, and the phlogifticated air iu the other. 

This fuppofition is ftrengthened by finding that whether the 
produce be acid, or pure water, the two kinds of air unite in 
nearly the fame proportions. But fince water has an affinity 
to almoft every fubftance in nature, and a peculiarly ftrong one 
to the acid aod alkaline principles, it may be impoftible that it 
ihould be wholly free from them; and if they be in proper 
proportions to faQirate one another, and in the fame quantities, 
their prefeiice may never appear. 

As the reafon why, in my former experiments, I always 

produced an acid liquori and never pure water, was 1x17 ufiog 

. too 



Decompofitkn tf depkkg^k^ti^ and infiammable Air. zzi • 
too great a' proportion of dephlogiflicated air; fo the reafoii 
why M- Lavoisier and his friends generally produced but 
little acid^ and at laft not >t all, muft have been, that the JIow 
combuftion which they made ufe of gave the principle of acidity 
in the dephlogifticated air, and the phlogjfton in the inflamnia- 
ble air, a better opportunity of efcaping, and forming the phlo- 
gifticated air in their refiduum, of which they have not pub*' 
lilhed any fatisfaftory account * ; and it is probable^ that the 
weight of thele cletiaents compared with that of the water 
which forms the bafis ctf the two kinds of air, may be very 
fraall. , That excellent, philofopher M. De.Luc fuppofes that 
they have even no weight at all. 

M. Lavoisier himfclf, I obferve, lays particular ftrefs, (p. 
262.) on the Jlownefs of the combuftion, as if he fufpeded it 
to be necefl'ary to his refult. This circumftance may alio 
account for my want of fuccefs in the attempts that I made to 
repeat his experiment : for whenever I made a ftream of in- 
flammable air to burn in a veflel of dephlogifticated air (which 
I contrived to do by means of a lefs expenfive, but I own a lefs 
accurate, apparatus than his) I always got fome acid, though 
lefs than in my own procefs ; but I made a larger and ftronger 
flame than I imagine M. Lavoisier chofc to produce. 

In the courfe of thefe experiments, I found, that when the in- 
flammable air 1 made ufe of was frona turnings of ^^ iron^ there 
was always a confiderable quantity of fixed air in the refiduum^ 
not lefs than one- tenth of a meafure, after the explofion of two 

♦ Since this was written, McflT. Fourcroy, Vauqjtelin, and Seouin, have 
publiihed a vciy particular account of their experiment ; from which it appears, 
that, after the combuAion of the two kinds of air, there was a pretty large refi- 
duum of phlogifticated air, more than was contained in the airs before combuflion. 
See 4»milu di Cbimif^ for April 1 79I1 p. 35* 

meafures 



iiz l!)r. Priebtley*s Experiments^ kc. 

ineafures of inflammable air and one of dephlogifticated ; 

whereas there was either no fixed air at all, or the flighteft 

appearance of it imaginable, when I made ufe of inflammable 

air from malleable iron^ extracted either by means of fteam or 

acids. 

The principal of thefe experiments, as well as thofe in my 
former Papers on ihis fubje^l, will be found to confirm the 
limilar ones of Mr. Cavendish ; but they prove the fource of 
the acid in the refults not to be what he imagined, viz. phh^ 
gijlicated air^ but the union of the dephlogifticated and in- 
flammable air ; and they alfo make it at leafl: doubtful, whe- 
ther thefe two kinds of air compofe purt water. 




[ a>3 3 



XrV. Experiments on Human Calculi. In a Letter from Mr, 
Timothy Lane, F, R, S, to William Pitcairn, Af. D, 



Read May 5, 17911 



s 1 R, 



IT will give me much fatlsfa^lion fliould the following ex- 
periments, made twenty years ago, fo far meet your ap- 
probation, as to be thought worthy the notice of the Royal 
Society. 

The Lixivium Saponarium of the late Pharmacopoeia, pre* 
pftred with the addition of fo much lime as nearly to free the 
fait of tartar of its fixed air •, having been ufed as a medicine 
for the ftone and gravel fome years before, and its cffeds 
found very unequal, I thought it aecefTary to examine 'dif- 
ferent calculi, then collefted, both as to the tSt(k of the above 
lixivrum, and of fire, upon them. 

Great difparity was obferved; &me being xHflblved, and 
others fcarcely altered in their iigure. 

When tried by fire, fome were Hfearly evaporated by a red 
heat, and others retained their form. 

Different parts even of the fame calculus, varied confi!- 
derably. 

^ See Letter to Dr, Hebekdeki Medical Tranfaftionii Vol. L p. zia. 

4 That 



224 M^' Lane's Experiments on 

That .1 might be better informed of the above, the experi- 
ments were repeated both by fire and lixivium, with greater 
accuracy, as follows. 

Fourteen fpecimens were fclefted, forac of which were 
parts of the fame calculus, and others different calculi. 

In the experiments by fire I was favoured with the affiftancc 
of Mr. Stanesby Alchorne, of the Tower, to whom were 
fent ten grains of each, in feparatc papers, which were num- 
bered. 

The contents of each paper were placed in feparate cupels^ 
under a muffle, the fame as is ufed by him for aflaying gold 
and filver. The fire was raifed gradually, till the furnace was 
fully heated : the time from raifing the fire to the taking them 
out again was three hours, when it was concluded, that what- 
ever volatile matter they contained was expelled. 

The fame quantity as above, of each (pecimen, being put 
Into feparate numbered phials, with one ounce meafure of the 
lixivium in each, continued forty-eight hours ; the phials were 
frequently (haken to forward the folution. 

The clear liquor of each phial was decanted into frefii phials^ 
and a quarter of an ounce more lixivium was added to foch as 
were undiflblved ; after twenty- four hours they were poured out 
of the phials into feparate filtering papers, each numbered, and 
the phials wafhed with diftilled water, which was alfo poured 
into the papers, fo that all that remained undiflblved might be 
detained by the papers, which with their contents were care- 
fully dried. 



The 





jH!mm« GtiSnNSL 




Th» remains of each 


Unfublimcd. 


Undiflblved. 




CfniM. 


Grabi. 


N' I. 


If 


1 


2. 


il 


2 


3- 


i 


f 


4. 


U 


2 


5« 


i 





6. 


3i 


af 


7- 


31 


6 


8. 


6 


8| 


9- 


6{ 


6| 


xo. 


6f 


7f 


11. 


1 


f 


12. 


1 





'3- 


5i 


4 


14' 


6 


5J 



aa; 



Appearances rf each after Cakmatitm. 

W u 3* 7* 3. Mt a fine white aiid ibft powden 

N^ 4» 5* ,11. 12. kft a white and gritty powder. 

N"" 2. 6. 9* 10. 14, were partly in powder white and gritty, 
vdth ibme lumps of a dark colouft as if not fully calcined. 

N^ 13* Of this the figure was jiot greatly altered ; it KOMiiied 
hardt and part of it appeared as if inclined to flux. 

Jjfter being in the Uxiviumforty^eigbt hours. 

NT 8. 9. 1^. 14. were found foft. 
N"" 7* and lo. remained hard. 
Vol. LXXXI. H h Thefe 



226 Mr. Lane's Experiments on 

Thefe fix were feparately taken out.pf the lixivium and put 
into a mortar, and rubbed or broken, and then carefully re- 
turned to their feparate phiaU b^fbl'^eithb fecond addition of 
lixivium, in order tai:brward thei^l^tion. 

Specimens defer ibed. ** 

N^ I • The external part of a laminated calculus, of a light 
yeliowi(h brown colour *. 

N"" 2. The external part of a calculus, in colour like dirty 
tobacco-pipe clay +. 

N*" 3» A light-brown laminated calculmf^ 

N"* 4* and j. Two. fpecimens from one calculus ; of which 
N"* 4. is the external coat, of a dirty tobacco^pipe-clay colour. 

N^ 5. The internal part of N« 4.,, yellowifh like N« 1. 

N^ 6. A calculus taken out of the urethra; agreyifli white^ 
inclining to yellow, of a porous texture. 

N"* 7. A calculus about the fize of a nutowg, taken from a 
child of a year old, given me by the late Mr. Pott ; afli* 
coloured, in waves of different (hades, laminated and hard. 

N** 8. A dark-brown r^ty hard calculus, of the mulberry kind, 

N'' 9. and 10. Two fpecimens from one calculus ; of which 
N^ 9. is the external whitifli part, which appeared like a coat 
of calcareous earth, covering an irregular mulbeny calculus |. 

* The nucleus, fo called; being the central part, was of a touch deeper 
colovf, and had been found not to foluble in lixivium as the light*brown pa^. 

t The nucleus was of a bright yellow, and mow fohible in lixtviuin than the 
whiti(h part. . . 

X The covering of this calculus induced roe tafiifpeA that lime or lime-water 
might have been taken, and, by being decompognded by freih urine, containing 
fixed aiTi form this covering. Other calculi have aflbrded the fame fufpicions. 

In future^ an account of medicines taken might aflford much information,, 
joined with the examtnatioa of different parts of large catculi taken out of the 
bladder, 

N« 10. 



Human^CalcuH. 227 

N^ lo. The brown mulberry part covered by N° 9. The 
three following are parts of one large, laminated calculus ; of 
whlcfai^ ' . ! " • . 

N^ II* Is the external lamina, of a brownifli yellow. 

N"" 12. The central part, called the nucleus, of a pale 
orange colour. 

N** 13. Some of the'Iatxiin^, between the nucleus and the 
external coat, of a fparkling appearance. 

N^ 14.^ A whiti(h, porous, and eafily broken calculus. 

The^ex^erimc;nts by fire explain the unequal accounts of 
authors, refpe^ing the component parts of calculi. 

In general, thofe which contain the largefl proportion of 
volatile parts >yere moft foluble in lixivium. 

The in£)lubility of fome explains the want of fuccefs in 
feyer^l cafes, where lixivium, foap, and lime-water, have been, 
given as reoaedies. 

The ib^ubiltty of others^ joined with the teftimony of re- 
putable authors, and my own experience for near thirty years, 
cojiifirm the.falutary effeds of lixivium in many cafe3. . 

le. frequently .happens^ in fits of the gravel and fbone, that 
gravel or fmall pieces of calculi are difcharged^ which ihould 
be examined. 

. If perfectly foluble in lixivium (Aq. kalipurij^ the remedy 
is obvious ; if imperfedly^ doubtful ; if iufoluble, lixiviuin 
will only irritate, without benefit. 

I am, &:c. ^ . 

T. LANE. 

AldeHgat'e-fireet^ ' "^ 

March lo, 1791. 

Hh2 



t «« J 



XV. Cbermes Laeca, By William Roxburgh, M, D. $f 
. Samulcocca* Commmicattd liyV^iaK^^}x&i)AflLU.F,R.S» 

r 

Read May 19, I'j^i* 

00 ME pieces of very frefli-loofcing lac, adherihg to (mall 
*^ branches of Mimofa-cinerea*,' were brouglit me ffoln the 
mountains, on the 2bth of Noveml^er, 1789. 1 kept thein 
carefully in wide*mouthed Cryftal bottles, (lightly covered ; and 
this day, the '4th ort)ecembe'r, fourteen days frdtothetttfi6 
they came from the hills, thoufands of exceedin|; minute rfed 
animals were obferved' crawling about the lac and the branches 
it adhered to, and ftill more were iffuing from fmalt hofes on 
the (urface of the cells, fiy the afliflance of gla'(ies, fcrlall itj^-' 
perforated excrefcences were alfp obfcrved, inferfperfed amohg- 
thefe holes, two, regularly, to each hole, crowned w^h fotne 
very fine white hairs, which being rubbed off,' tWp white fpots 
appeared. The animats, when (ingle, rah about pretty brifltly ; 
but, in general, on opening the cells, they w6re to mirtierous 
as to Be crowded over one another. The fubftance o'f Which llie 
cells were formed caiinot be better defcribed, with rtfpteQ! to ap* 
pearance, than by (aying it is like fh6 tranfparenC amber that 
beads are made of. The external covering bf the' cells may be 
about half a line thick, is remarkably ftrong, and able to re(i(t 
injuries : the partitions arr much thinner. The cells are in 
general irregular fquares, pentagons, and hexagons, about an 

^ Lac, on this coaft, is always found upon the three followiBg fpecic^^ of Mi* 
mofa ; ift, a new fpecies, called by the Geotooa Conda corioda ; ad, Mimofa 
glauca of Koenig; and, 3dly, Mimofa cinerea of Lxnnjevs. 

eighth 



Dk ^oxbvrgh's yfecount J Sec. la^ 

eighth of an tiKh in diameter, and a quarter of an iiich deep : 
they have no communication with each other. All thofe I 
openeii, during the time the animah were liTuing from them, 
contained in one iide^ and which occupied half the cell, a 
imail bag, filled with a thick red jellj-like liquor, replete with 
what I take to be eggs. Thefe bags, or utricnli, adhere to the 
boltomof the cel^s, and have each two necks, which pafs through 
perforations in the external coat of the cells, forming the before* 
mentioned excrefcencea, ending in fome very fine hairs. 

The other half of the cells have a diftant opening, and 
ccntaiin a wliite fuhftaoce, like fome few filaments of cottoa 
nilled together, and a number of the little red infe^ themielves 
crawlbig about, ready to make their exit/ Their portion o£ 
each cell is about x half; and, I think, muflr have con- 
tained near one hundred of thefe animalsi. Other cells, lefs 
forw&rdv contained in this half with one opening, a thicks 
zed, darkblood^^coloured liquor^ with numbers of exceedingly 
minute eggs, oBKaiiy times f mailer than thofe found in thefmall 
bags which occitpied the other half of the cells. Several of 
theleinfo^I obforved to have drawn up their legs,, and to 
fie fbt; Irfaey did oot move on: being touched;: nor did they 
fiiew ai^ figQS of fifo upon the greateft irritation *. 

Dec 5- The faine nxinQbe: hexapodes continue ififuing £mai 
difiir ceUa in numbeni. 

. DoCi 6^ The miale infoSt^ I have found to*da)r, at kaft what 
I dHuak is fuch. A few of them am cooftancly running abputt 
and .over the little ned infofts^ (which I (hall now call the 
foioale)'moft a6kcvely: as yet they are fcsirce, not more, I 
idiagiiie^ than it to 5000 females, but they are four or five 
their fo&e. 



* It will appear in the fcquel, that thcle were on the point of tnmtformation 
into the ptipa ilate. 

I To-day 



230 Dr. Roxburgh's Acc(mnt of 

To-day the female infe£ls continue iiruing in great nunfibersy 
and move about as before, 

Dec. 7. The fmall red or female infefts, areftill more nume- 
rous, and move about as before. The winged or male infects, arc 
ftill very few, but continue a£tive. There have been frefli leaves 
and bits of the brancfa^es of Mimofa cinerea, and Mimofa intfia^ 
put in to them. They go over them indifferently, without 
Ihewing any preference or inclination to work, or to cbpnlate. 
I opened a cell, from whence I thought the winged flies had 
come, and found feveral (eight or ten) ftruggling to ihake off 
their incumbrances. They were in one of thofe utriculi dien^ 
tioned before, which end in two mouths, (but i;p* with 
fine white hairs ; but one of them was open for the exit of the 
flies ; the other would, no doubt, have opened in due . time. 
This utriculus I found now perfectly dry ; add could plainly^ 
fee it was divided into minute cells, by exceedingly thin mem*, 
hraneous partitions. I imagine, j^efbre any of the flies. made 
their efcape, it might have contaihed about iixteen or ^enty.. la 
the minute cells, with the living, floes^ orifrdm ^wiiencer'thcy hacL 
made their efcape, were fmall dark-coloturedcomprefied grains. 

March 26, 1790, I found fbnoe branched of tTieiaiae;fi)rc o£ 
Mimofa, with numbers of the minote; red liexappdesy men* 
tioned in December (feemingly* iit theic pupa- fbte), adheiftig 
to them. They are of various (izes, from hklf.a linetoaiinfe 
and a half in length; • I found inhny of the. large ones empity. 
They have au rodnd opening at the: loiwer end, withi agnail 
round operculum, or lid^ which now loofely covers the empty- 
hu(k or (hell : the iniide of thefe. is linedt with a fnrall. white 
metabrane ; i others were dill (hut, fome>w)ETerdpening,* andfome 
half open, with the infe£ts projecting more orlefs, ^and Uimt 
cxtricatinc; themfelves entirely. ^ . 

. .. .Icppenpd 
I 



. /^ Chefmes Lacca. 231 

1 I.tfpeDcd (bene of the middle- fized^ and found they con- 
tained a thick* deep blood-cc^oured liquid; others, flill larger, 
put on the appearance of the fly, which yras foon to iflue, 
rettoi^wdo. : 

. \ Dijjl»ipt$(m,pf tbc male lac infe£i in its perfeSiftate. 

It IS then about the (ize of a very fmall fly, and exceedingly 
active ; the larva and pupa (late, I an» as yet unacquainted 
with. , . ' 

Head obtufe ; between the feyes a beautiful, (hining green.' 
JSy^x, black, very large in proportion to the animal. 
Antenna^ clavated, feathered, about two thirds the length 
of the body ; below the middle, an ^articulation^ fuch 
as thofe in the legs. 
Mouth : I could not difiindly fee it. 
Trunk J oval, brown. 

. Jbdomefij oblong, length of the trunk and head. 
"Extremities. . Vide p. 232. 

I^g^3 fix ; with them it runs brilkly, and jumps actively* 
JVingSy four, membranaceous, longer than the abdomen, 
incumbent ; the anterior pair twice the flze of the 
poflerior. 
jH?//, none«. 

Defiription of the female lac infeff. 

Larw^ red, very minute, requiring a good lens to diftioguiih 

its parts. 
Head^ fcarcely to be dtftinguifhed from the trunk. 

Anteufue^ filiform, bifid, hairy, length of the infed. 
Eyes: in the back part of the trunk are two* minute eleva* 
tions^ which may be they. 

Mouthy 



%j% Dr. Rdx&VR«s*« Aeetma of 

Mouthy on the middle of «he breaft, between tke tnrft pntr 
of legSi which the little animal projeAs ou being in* 
jured, otherwtfe ifcannot be feea. 

Trunk and Abdomen^ oblong, comprefled, tapering M|)ia1l7 
towards each end, croiTed with twelve annular fegments^ 
margins very flat^ and &em to be masked wkh a doiiUe line. 

Extremities. 

Legs^ (ixy running, does «ot jump. 
Wings^ none. 

Tail^ two (lender white hairs, as long as the antennae, 
with a white point, which maj be called the riimp, 
between them. 

Pupa : the duration and peregrinations of the larvae ieem very 
ihort and confined ; for, in a few days after ifluing from 
their cells they fix themfelves on -the fmall, but hard, woody 
branches of the tree they were produced on ; it feeming 
impoftible that they can in this ftate tran^rt themfelves 
to any other. ^ About the end of December, or beginning 
of January^ they have done ifluing from their cells, and 
are Clicking fsift to the branches, regularly with their 
heads towards the extremity of the branch. The legs, 
antennae, and tail, are now entirely gone* Their prpgrefs 
through this ftate is How, requiring about three .months. 
Soon after they have fettled themfelvesi they become 
covered with a bafd, Imttie, gamMvcoloimd cruft, fimi- 
kr «o the lac of which the ceUs ^le made, but af a 
brighter colour. They retain only a rude refixnUaice c^ 
their former flnpe. Aboat the end lof Maoch thc^ Imm, 
acquired throe or four titnes their or^osd fisej a\fiiiall» 
txHtnd lid €r <sovc(r aa now oUesvcid Ht 4he ilower part, 
which opens, but does not altwag^s fall i off, 4KAil; gives a 
rftrograde paflage for the fly, now in its perfeft ftate. 

The 



the Chermes Lacca« z^^ 

The iofed: ifl it9 perfe£k ftate is rather fmaller than the male^ 

of a brighter red colour^ ^nd lefs zBxvt. 
'Hiad^ fmall in proportion to the body, pointed; 
^yes^ very minute. 
Antenna^ filiform^ not articulated as hi the male^ fpread* 

ing, foroewhat (horter than the infeft. ^ 
Mouth : I could not difcover it didindly. 
^runi^ red, almoft orbicular. 

jlhdomeni red, oblong, compofed of twelve annular fegments. 
Extremtitu 

Legs^ fix, for running or jumping. 

Wings^ two, incumbent, longer than the abdomen, tranf- 

parent* 
7a/7, two white hairs as long as the infect* 
With regard to the oeconomy of thefe little animals, I mud, 
for the prefent, be filent ; having little morp than conjecture 
to offer on that head. 

The eggs, and dark-coloured glutinous liquor they are found 
an, communicate to water a moft beautiful red colour, whUe 
freih. After they have beep <Jried, the colour they give to 
water is lefs bright ; it would therefore be well worth while 
for thofe, who are iituated near places where the lac is plenti- 
fully found, to try to extraA and preferve the colouring prin* 
ciples by fuch means as would prevent them from being injured 
by keeping. I doubt not but in time a method may be difco- 
vered to render this colouring matter as valuable as cochineal. 

Mr. Hellot's procefa for extra&ing the colouring matter 
from dry lac deferves to be tried with the frefli lac in the 
month of October, or beginnihg of November, before the 
infers have acquired life ; for I found the deepeft and beft 
colour was procured from the eggs while mixed with their nid^is. 
Vol. LXXXI. 1 i His 



234 -^^- Roxburgh's Account of 

His proccfs is as follows. Let fome powdered gum lac be 
digtfted two hours in a deco£lion of comfrey root, by which a 
fine^rlmfon colour is given to the water, and the gum is ren- 
dered pale or ftraw coloured. To this tindurc, poured ofF 
clear, let a folution of alum be added ; and when the colouring 
matter has fubfided, let it be feparated from the clear liquor 
and dried ; it will weigh about one fifth of the quantity of 
lac employed. This dried fecula is to be diflblved or dlfFufed 
in warm water ; and fome folution of tin is to be added to it, 
by which it acquires a vivid fcarlet colour. This liquor is to 
be added to a folution of tartar in boiling water ; and thus the 
dye is prepared. 

In India comfrey roots are not to be had ; but any other muci- 
laginous root, gum, or bark, would probably anfwer equally 
•well. On fome parts on the Coromandel coaft, if not over it 
all, a decoftion of the feeds of a very common plant (CaflTa 
tora of LiNN-ffiUs), which is exceedingly mucilaginous, is 
ufed by the dyers of cotton cloth blue, to help to prepare the 
blue vat. It fufpends the indigo till a fermentation takes place 
to diflfolve it, and alfo helps to bring about that fermentatiork 
earlier than it otherwifc would. The gum lac (or rather 
refin) itfelf is known to be perfectly foluble in fpirits of wine. 
The empty hulks which covered the pupa are alfo foluble in 
Spirits, but without a very large proportion of the fpirits is 
ufed, it foon becomes thick, like a jelly. Four grains com- 
municated that quality to three drams of reSified fpirits of 
wine. This jelly is very difficult of folution in fpirits ; a 
month has not efFefted it in a heat of from 80 to 90 degreers 
of Fahrenheit's fcale. The fubftance of which thefe hufks 
are compofed, is an exudation from the larvae themfclvcs, 
which becomes hard by expofure to the air. The cells fcem 
7 to 



the Chermes Lacca. aj^ 

to be made of a very difFercnt fubftancc; what that Is, and^he 
maDiier in which they are made, remains fllli to be difcovered. 

Explanation of the figures. Tab. VI. 

\% A piece of lac on a fmall branch of Mimofa cinerea, 
natural fize. 

2. The outfide of the top of a cell, with its three openings ; 
the white one with the hairs is ftill unopened. 

3. One of the utriculi for the male flics, with its two necks, 
which correfpond with the two upper apertures in fig. 2. 

4. One of the eggs found in the utriculus, fig. 3. which 
produces the male flies. 

5* The male fly in its perfect flate. 

6. Small compreflfed dry grains, found in the cellulas with 
the male flies. The lafl: five figures are all much magnified. 

7. A fmall bit of a branch of Mimofa cinerea, with the 
female infeds in their pupa (late, natural fize. 

8. One of the eggs which produce the female larva. They 
are always in that portion of the cell from whence the larva 
iflfues. 

9. The female larva. 

10. •— pupa. 

11. ■■ with the lid opening, and the infedb 
protruding. 

12. The female fly in its complete ftate. 

The laft five figures are much magnified* 



li 1 



C *s« 3 



XVI* The Longitudes tf Dunkirk and Paris from Greenwich, 
deduced from the Triangular Meafurement in 1787, 1788^ 
fuppofing the Earth to be an Ellipfoid. By Mr. Ifaac Dalby ;. 
communicated by Charles Blagden^ M. D. Sec% R. S. 



Read May r^, 1791. 

INuhe account of the Trigonometrical Operation in I7?7# 
1788, which is given in the Philofophical Tranfaftions, 
Vol. LXXX. after the diftance of Dunkirk from the meridiaa 
of Greenwich has been determined on a parallel to the perpen- 
dicular at Greenwich, its longitude is found by fpherical com- 
putation, on a fuppofition, that the furface of a fphere nearly 
coincided with that of the earth in an eaiH: and weft diredtion, 
where the operation was performed ; and the magnitude of this 
fphere, or which amounts to the fame thing, the value in parts 
of a degree, &c. of a meafured arc on its furface (for as fuch 
the arc between the meridians of Botley Hill and Goudhurft 
m^y be confiderdd) has been deter^nined by a(3ual obfervation 
at two flations nearly in the latitude of Dunkirk ; and this 
independent of any hypothefis which can fenfibly afFefl: the 
conclufion. The principles, though not flri£lly geometrical, 
admit of little objection ; and therefore, as much care was taken 
in obferving the angles at theie ftations, upon which the direc- 
tions of the meridians depend, the longitude of Dunkirk (and 
confcquently that of Paris) as given in the Table, Vol. LXXX. 
2 p. 232. 



Mr. Daley's BeduStlon^ &c# ^^j 

p. a3a- muft be nearly true, whatever may be the real figure 
of the earth. But, it may be faid, that the arc between the 
meridians of Botley Hill and Goudhurft (i;'!) is too fliort to 
infer from obfervation the value of the arc between the meri« 
dians of Greenwich and Dunkirk (amounting to near a degree 
and a half), fufficiently accurate for finding the longitude to 
great precifion ; becaufe it has been remarked in the Appendix 
to the fame Volume, that an error of i'', in either of the 
horizontal angles at the above ftations, would cauie a variation 
of near b^' of a degree in the longitude of Dunkirk or Paris. 

M. BouGU£R*s fpheroid agreeing nearly with the meridional 
meafurements, it was adopted for the purpofes of latitude. But 
the degree perpendicular to the meridian in latitude 51* 6^ 53^^ 
is found to be 61248 fathoms (Vol. LXXX. p. 215.) which 
falls fhort of M. Bougubr's degree about 22 fathoms ; there- 
fore, fuppofing the directions of the meridians to have been 
very accurately determined, the earth cannot be this fpheroid, 
notwithftanding the ingenious hypothefis refpeding the curve 
of the meridian. But it is alfo well known, that the mea* 
fured degrees of latitude in difiFerent places are inconfifient with 
an elliptical meridian: for, fuppofe an ellipfoid to be deter- 
mined with the degrees found at the equator and polar circle, 
the computed degrees in middle latitudes will be much longer 
than the meafured ones, as it is well known ; and the whole 
meridional arc between Greenwich and Paris will, on fuch an 
ellipfoid, exceed the meafured arc by a quantity anfwering to 
about zi'^ of latitude. It is evident, however, that if we fuppofe 
fmall errors to have taken place in determining the celeftial arcs, 
or difiFerences of latitude in fome of the operations (for there 
is little doubt but the terreftrial menfuratiops in general have 

been 



J38 



ISr. Dalby's DeduSiion ef ih$ 
been made exa£l enough), it will be taiy to reconcile moft of 
the rcfults to an elHpfoid. 

The following computations of the longitude are made on a 
liippofition, that the earth is an ellipfbid, for the purpofe of 
CDinpnring the conclufions with what has been inferred fron^ 
oblervation. It will be feeii, that the ratio of the axes comes 
out very near the ratio affigned by Sir Isaac NbwtoNi or 229 
to 230. It is determined of fuch a magnitude, by adhering 
nearly to the mcafured arc of the meridian between Green- 
wfch and Paris, deduced from the late operation, that the 
computed meridional degrees differ but little from the meafured 
ones in five different places in middle latitudes ; but the defeats 
at the equator and polar circle are fuppofed to be nearly equal 
to each other. This will be feen better by the following com- 
parative view of the mcafured and computed degrees in the 
fame latitudes. 



According t9 


Lat. 


Meafured, 


Com" 


Excefs &r de^ 




• 




puftd. 


feSi im mea^ 




/ 


Fath. 


Path. 


fund arc. 


M. CONDAMINE, &C. 





60481 


60344 


+ >37 


Mason and Dixon, 


39 la 


60628 


60682 


- 54 


BOSCOVICH, &c. 


43 


60725 


60738 


- >3 


Cassini, &c. 


45 


60778 


60768 


+ 10 


L1E8GANIG*, 


48 43 


60839 


60823 


+ 16 



^Arc from latitude "^ 
French and JEir^AI^J 48^ 50' 14'' to I160656 

I 5^28' 40" J 
Macpertuis, &c. 66 20 61 194 



160662 



- 6 



61057 + 137 

In the five comparifons, from latitude 39** i%^ to Green- 
wich, the greateft error (54 fathoms) anfwers to about 3'' of 
the celeftial arc : neither of the other four differences amounts 
* From the late Gen. Roy's Paper io the Phil. Trant 1787, 

to 



Longiiudes of Dunkirk and Paris^ 235 

to i"'. The determinafion of M, BficcARi A is not brought into 
thecomparifon, becaufe his meafurcd degree in latitude 44** 44^ 
is longer than the meafured one in latitude 45**. 

The longitude of Dunkirk on this ellipfoid is found to be 
9 m. 29.8 s. in time ; and confequently that of Paris 9 m. 
2o|s., which is about li s. more than that inferred from 
the value of the meafured arc between Goudhurft and the 
meridian of Botley Hill ; and therefore the fum of the two 
horizontal angles at thefe (lations would, on this ellipfoid, be 
only about 4'^ lefs than thofe found by aftual obfervation. 

Method of computation. 

On an ellipfoid, where the degrees of the meridian at the 
equator and polar circle are 60481 and 61 194 fathoms refpec- 
tively, the degree in latitude 50** 9^i (the middle latitude be* 
tween Greenwich and Paris) will be 6098 1 fathoms, exceeding 
the meafured degree by 140 fathoms (Vol. LXXX. p. 225.) ; 
therefore, if each of the former degrees was about 140 fa- 
thoms lefs, the computed and meafured arcs in latitude sd'^^i 
would be nearly the fame. But, that they alfo may nearly 
agree in latitude 45% let the degrees at the equator, and in 
latitude 50'' 9'!, be taken 60344 and 60844; then, from thefe 
two degrees, the ratio of the axes will be found as the tan- 
gents of the arcs 50'' 9^! and 50® ^' 3S^ ii ^^^^ ^^^^ femi-axes 
3489932 and 3473656 fathoms *. 

The 

* Determined thus : If right lines are drawn perpendicular to thc'curve oi iconic 

/eSiom to meet the axis, it is known, that tin radii of curvature at the points in the 

cur^efrom wbetice thtfe lines are drawn^ will he as the cubes of thefe b'ues. Hence, if PC, 

GB, EC^Tab, VII. fig. i.), are perpendicular to the curve, the radii.of curvature 

at 



3140 . Mr. Dalby*s DeduStion (f the 

The length of the whole meridional arc between Greeni;vich 
and Paris on this ellipfoid is fix fathoms greater than the mea* 
fured arc; the degree in latitude 48'' 43% 16 fathoms lefs; in 
latitude 45% 10 fathoms lefs; in 43% 13. fathoms greater; 
and that in latitude 39^ i%\ 54 fathoms greater. The degrees 
^ the equator and polar circle are confiderahly lefs than the 
meafured onest conformable to the hypothefis. 

Suppofe CE, CP (fig. !•), are the greater and lefs fem^i- 
axes of the ellipfoid ; G Greenwich ; PGE its meridian ; PD 
the meridian of Dunkirk ; and let GB A be perpendicular to 
the curve of the meridian at G ; then GA will be the fhorter 
axis of the elliptical fe£tion which is the perpendicular to the 

pcT 

at F, G, Ey will be as PC'» GE', and -^—\ , becattfe at tkc point £ (or e^ua- 

PC* 

tor] the line fo drawn will become the radius of curvature itfelf, or -rr- There« 

C£ 

fore GB' : — — :: rod. cunv. at G^ rod. curv.^t E :: length tf a Jeg^ in the 

0£ I 

.2at. of G : length of a deg. at £, the equator. Let the arc £RL be defcribed 
with the radius CE; 4raw CR parallel toGB, RS parallel to PC, and join OK; 
then, by the nature cf Hie ellipfe, CR (C£) 1 CK :: GB : half the paramtur^ or 

rL ; therefore CE' ; CK' :; GB» xZLA :: 60844 : 60344 (fufpcfing the lot. 
CE C£ 1 



^f the point G to te 50^ 9'i), or CE (CR) : CK :; 60844!} : 60344} f; but 

CR : CK ixjine SKC ijine KRC {co^lat.) ; therefore, ^H^x cojme lot. = 

60344^ 

Jne SKC; hence the angle SCK is given (50° i' 3S"i)i therefore, as ta»g. 

SCK : tang. lat. (SCR) :: SK : SR ;: iejerfemi-axit C? : greater CE. And putting 

</= 57.2957 79, &c, the degrees in the circular arc which is equal to the radius) we have 

rr^cSTl ^ ^344 ^'.^ 348993* fathoms the longer fcmi-axis; and 

tang, lat. _ . , ^ ^ 

^-^^ X 60344 ^=347 3656, the fliortcr, ' 



tang. 

tan^ 

tang, 



meridian 



Longitudes of Dunkirk and Paria, 241 

meridian at Greenwich, and the angle EBG will be the lati* 
tudc of Greenwich, or fi"* 28^ 4o''^ Let HO (parallel to 
GA) be the fcftidn of the parallel to that perpendicular, pa fling 
through Dunkirk. Then by the Table, p. 232. (VoLLXXX.) 
the arc GH is 152549 feet ; but this arc exceeds the real dif- 
tahca of the parallels GA, HO, not more than a fathom ; 
therefore this diftancc may be taken = 25424 fathoms. Now 
thefe£tionsGA, HO, of the ellipfoid being fimilar, fi;om the 
known properties of the figure, we (hall get HO the (hotter 
axis of the fedion of the parallel — 6959396, its longer axis 
=6979374, and HW=353i757 fathoms, W being the point 
where HO cuts the axis PI of the ellipfoid. Hence, if D be 
Dunkirk, and the arc HD the meafured arc of the parallel, we 
have given the length of this arc, or 547058 feet (Table, p* 
232.) = 91 176 fathoms, and al(b the point W in the lefler axis 
of the fe&ion HO, to determine the angle H WD in the plane 
x)f this fediou. But reverting the feries which exhibits the 
length of an elliptical arc in terms of the abfcifs and ordinate^ 
Villi be of little ufe in the prefent cafe, where the arc and its 
chord are very near of the fame length : For, let HKOL (fig. 
2.) be the feftion of the parallel, where HO = 6959396, and 
KL=» 6979374, are the axes; and HW= 3531757, as in^. 
J. ; alfo, fuppofe HS is the radius of curvature at H, or at the 
middle of HD ; then, if we conceive the arc HD to be a right 
line, or defcribed with the radius HW, or with HS (3499700) 
and thence determine the angle SWD from the two fides SD, 
SW, and the included angle (the fupplement of HSD) ; in 
cither cafe we get the angle HWD the fame, or 1^ 28^ 44^^8 
to .within i^\ This angle bemg obtained, the inclination of 
the planes PHW, PDW (the planes of the meridians of 
Vol. LXXXI. K k Green- 



142 Mr. Oalby^s Dedu^hn of the 

Gfeciitvich and Dunkirk, Jig. i.), or the longitude of the poin* 
D, will be found by the common proportion which in a right- 
r.ngled fphcrical triangle determines an angle when the legs 
are given : thi$ will be obvious bj conceiving a fphere (of any 
magnitude) to be defcribed about W as a center. 

Hence, as rad^ : caiang. angle HWD (i® 2%^ 44^^.^) *"fi^ 
angle HWP (38^ 31^ 20'') : cotang. 2^ 22' 26''!, the incli- 
nation of the planes of the meridians PH, PD, or longitude 
of Dunkirk on this ellipfoid. And as the difference of meri- 
dians of Paris and Dunkirk is 2^ 2i^^9 (for this will not be 
materially affcfted by different hypotheies) the longitude of 
Paris will be 9 m. 20 j- s. in time. The longitude of Dunkirk 
from Paris (2^ <i^^*9) ^^ ^^^ mean longitude deduced at p. 225* 
(Vol. LXXX.% which is only i^^i lefs than that given in the 
CMMfffance des Ttmps^ 1 788. 

The method of computing the latitude of the point D (was 

It ncceflary) is thus: as rad. : cofintDWH r. cofine HWP : 

tefine DWP ; and fince the point W in the axis PW is given^ 

and alfo the angle DWP in the plane of the meridian PD (by 

the foregoing proportion), the point D will be determined by 

tbe properties of the ellipfe ; which in fad is nothing more 

than finding the inclination of the vertical at the point D with 

the given line DW^ which inclination added to the angle 

DWP, gives the co-ktitude of the point D. And hence may 

be evinced the truth of what is advanced at p« 199. (VoL 

LXXX.), that if the value tf am are en a fpheroid^ coffered 

^s an are of a great eirck perpendicular /^ the mendian, be given^ 

the longitude may he found iy fpheried emfputMtim^ but not the 

latitude. For conceive the arc HD to be perpencficolar to the 

meridian at H| then the ao^le HWP would be the co^latitude 

4 af 



LongUudes of Dunkirk and Paris. 24 j 

cf the point H ; and the former proportion would give the 
longitude of D, whether the figure was a (phcrc or fphcroid ; 
And the angle DWP (found by the latter proportion) would be 
the co-latitude of D fuppofing it a fphere, in which cafe the 
point W becomes the center; but this will not hold in d 
fpheroid, becaufe DV7 would not be perpendicular to the meri* 
dian at D. 

The forgoing method of computing the longitude from the 
meafured arc of a parallel on a given ellipfoid (though evidently 
the direct one), will be tedious, efpecially when the lengths of 
the meafured arcs (GH, HD) are very confiderable. But whett 
the latitude of the point H is determined from the meafured arc 
GH (on the known meridian), and the extent of the other arc 
(HD), or rather the angle HWD, is not more than two or 
three degrees, the fame conclufions, extremely near, may be 
bbtained in the following manner, which is nearly the fame zt 
the method ufed in computing the longitudes in the Tible of 
General refults, p. 23a. (Vol. LXXX.)« 

Suppofc G and D (fig, i.) to be Greenwich and Dunkirk ; PH, 
FD, their itieridians, as before; and let HD(inftead of its being 
a parallel to the perpendicular at Greenwich) be an arc of an 
cUipfe cutting the meridian of Oreeni^ich at right angles, fuppofb 
in the point H, Then the arc GH being = 152549 + 50 feet 
nearly (becaufe the ellipfe which pafTes through D, arid is a)t 
nght angles to the meridian PG^ will fall about 50 feet to the 
fouth of the point cut by the parallel), therefore the value of 
the arc GH^ or 15433 ^ithcMns, will, on this ellipfoid, be 
±$^ 4".4j aiid cionfeqileAtly the aftgte PWH, or the co-^lati- 
tude of H^ is 38® 56' ^4^^4^ Now, the radius of curvature 
^f this perpendicular ellipfe at H, the extremity of its lefTer 

K k 2 axis, 



844 ^^^ Dalbv*s Dedu3ion ef the 

axis, will be 3499798 fathoms*! which, divided ^y SV^9S1^h 
&c. (the degrees in the circular arc which is equal to the radius), 
gives 61083 fathoms for a degree on this ellipfe, coufidered as 
a great circle perpendicular to the meridian at the pouit li on 
the ellipfoid; and fince the length of this arc (HD) will be 
nearly the fame as that of the parallel, or 91 176 fathoms, its 
value will be i** zp^ 33'^-6 (the arc DH, or rather the angle 
DWH). Hence, as rad. : cotang. i" 29' 33'^6 (HWD) v. fine 
38° 56' 24''.4 (HWP) : cotang. 2^ 22^ 26''.8, the longitude 
of D, or Dunkirk, the fame as before, very near ; hence the 
longitude of Paris will be 2® 20^^ 4^^j>. But the fame may be 
obtained from the mean diftance of the meridians of Green- 
wich and Paris, or 537950 feet. See p. 599. in the Appendix 
to Vol. LXXX. 

It appears from the foregoing hypotheiis, that the meafured de« 
grees of the meridian in middle latitudes will anfwer nearly on an 
ellipfoid whofe axes are in the ratio afligned by Sir Isaac New* 
TON. But this will receive further confirmation from the fifth 
ellipfoid in the fecond Table, p. 23 z. (Vol. LXXX.), where the 
near agreement between the computed and meafured arc of the 
meridian between Greenwich and Perpignan (differing but about 
52 fathoms in the extent of 8* 46^ 4V'') would be fomewhat 
cxtiraordinary, were we certain that the latitude of Perpignaa 
(42'' 41^ 56^^ is corred; but thia ia fufpe^led by M. de la 

* It it not neceffaiy to detenpine Oe axet of t&ii ellipfe, bccaule when HW 
is perpendicular to the cnnre of the meridian, it will (by the nature of the figure) 
be the radius of curvature of the are HD at the point H. Hence, if we put ir 
for the €et09g. and c for the cpfiu of the latitude of the point H, and let « denote 

of theelliple. 

Caiub» 



rtti/oxTnuts.Vo/. LXXXI. Tah, VII. //. 244. 




LongituJes of Dunkirk and Paris. 245 

Catllb. Sec Mem, ie VAcad. 1758. The computed arc, 
however, between Greenwich and Paris is 19 fathoms longer 
than the meafured arc, which anfwers to a little more than v'^ 
of latitude. 

The longitude of Paris on this ellipfoid ijs 9 m. 20,^ $• 
If it be contended, that the operations at the equator and polar 
circle were as correft as thofe executed for the like purpofe 
in middle latitudes ; and that a kind of mean between the ex* 
treme refults ought to be preferred ; we (hall flill get an ellip- 
foid, whofe axes are nearly as 229 to 230, by taking the 
degrees at the equator and polar circle each 70 fathoms lefs, 
and that in latitude 50* f)\ as much greater than the meafured 
ones ; and the longitude of Paris will be found 9m. \^^-^%. 
But the computed meridional arc between Greenwich and Paris 
will exceed the meafured one by a quantity anfwering to about 
11'^ of latitude. 

It is almoft needlefs to obferve, that the longitude of Paris 
(9 m. 20 s.) deduced by Dr. Maskeltnb from the different 
refults found by agronomical obfervations (Phil. Tranf. 1787) 
agrees to lefs than half a fecond with either of the above 
determinations. 



N. B. lo the Tabic of General Refults, p. 23a. Vol. LXXX. uad \V ^bf' for 
tkc loDgitude of Wrotham Hill ; thia ihould have been correfted la the Appendix. 



^•U9» 



[ *46 ] 



XVII, On the Method of determining^ from the real Probabilities 
of Life^ the Values of contingent Reverjions in which Three 
Lives are involved in the Survivorjhip. By Mr. William 
Morgan, K -R. S. 



Read May 26, 1791* 

HAVING been encouraged to the further purfuit of the 
dodrine of furviyorftiips by the very honourable man- 
ner in which my two former Papers on this fubjed were 
received by the Royal Society, I think it my duty to fubmit 
the refult of my labours to their confideration. The folutions 
of fome of the following problems might have been derived 
from thofe which I have already communicated ; but the direft 
inveftigation of each Separate problem being certainly more 
fatisfa£tory, and the rules obtained by this means in general 
more fimple, I have coniidered no problem as conne^led with 
another, except the relation between them either immediately 
arifes from the folution, or is necefiary to prove the truth of 
it. Being anxious to render myfelf as concife as pofiible, I 
have been minute only in the inveftigatton of the firft pro- 
blem) and hate done* little more than ftatb the contingencies 
which will determine the furvivorfhip in the others* By the 
afliftance, however, of thefe, and the operations which are 
detailed in my former Papern ttke theorems which I have given 
may be deduced without much difficulty. 



denote the value of an annuity on the refpe^tlve lives 
of A, B, or C. 



JMr. MoftGAN OH Survivor/hips. 247 

In order to prevent unneceffary repetitions, it may not be 
improper to begin with explaining the different fymbols which 
are ufed in the followic^ pages. 

B, 

C, J 

D^ denotes the value of S on the contingency of C*s fur-^ 
Tiving A (by my 2d prob. Vol. LXXVIIJ). 

£9 denotes the fame value on the contingency of B*s fur* 
viving A^ found by the fame problem. 

F| denotes the value of an annuity on a life one year younger 
than 6. 

G, denotes the value of the abfolute reverfion of S after the 
death of A.. 

H» denotes the value of an annuity on a X\£c one year younger 
than A» , 

Ky denotes the value of an annuity on a life one year younger 
than C» 

Ly denotes the value of an annuity oa the longeft of the 
three lives of A, B, and C. 

M> denc^s the value of S by the firft problem on the con* 
tiugency that A*s life (hall be the j(r^ that fails* 

N> denotes the value of an aniiutty oa a life one year older 
than A. 

Vy denotes the value of an annuity on a life one year older 
tkan B. 

R» denotes the value 1^ S on the contingency of B's dying 
after A (by my 3d prob. VoL LXXVm> 

Sf denotes the given fum. 

T» denotes the value of an annuity on a life one year older 
thanC. 

V9 denotes 



249 Mr. Morgan oh 

V, denotes the perpetuity. 

W, denotes the value of S on the contingency of C*s dying 
after A (by my 3d prob. Vol. LXXVIII). 

» and a denote the number of perfons living in a table of 
obfervations at the ages of H and A. 

/y /, Uf W9 Sec. denote the number of perfons living at the 
end of the ift, 2d, 3d, &c. years from the age of A. 

j3 and bf denote the number 6f perfons living at the ages of 
F and B. 

^f «» ^9 pf &c. denote the number of perfons living at the 
end of the ift, 2d, 3d, &c. years from the age of B, 

X and <: denote the number of perfons living at the ages of 
K and C. 

^f ^9 /» £9 ^c* denote the number of perfons living at the 
end of the 1 {(, ad, 3d, &c. years from the age of C. 

a\ af\ af'\ &c. ^ denote the decrements of life at the end 



b\ l/\ b"\ &c. 
c^ d\ d'\ &c. 



of the I ft, 2d, 3d, &c. years from the 
refpe£tive ages of A, B, and C. 
r, denotes the value of ^. i increafed by its intereft for a 
year. 

The combinations of two or three of the feveral letters A, 
By C, F, H, &c. denote the values of annuities on the joint 
continuance of two or three of thofe refpedive lives. 

PROBLEM I. 

To determine the value of a given fum, payable if A (hould 
be the/r^ that fails of the three lives A^ By aind C. 

SOLUTION. 

In order to receive the given fum in thefirftyeafy it is 
neceflary that one or other of four events ihould happen, ifty 

That 



Survivor/hJps. 249 

That all the three lives (hould foil, and that A (hould die firft. 
2dly, That B (hould die after A, and C live. 3dly, That C 
fliould die after A, and B live. 4thly, That A only fhould 
die, and B and C both live. Thefe feveral contingencies being 

_ rr ^ \ a' ^ b^m • c — d a' . b-^m , d cf • c-^U , m % o' • dm 

expreffedby ^^ , ,,,, > ,,,, ' ^°^ - ^T » 

refpeaively, their fum will be=4 x fl'+f:zif +°^'+tJ.^, j^ 

* ' abc ^ ^ o 

the iecdnd and following years one or other of the fame events 
xnuft take place in order to receive the given fum ; that is, they 
muft either all three die* A dying firft ; or only A and B muft 
die, A dying firft ; or only A and C muft die, A dying firft ; 
or only A muft die, and B and C both live. The different 
fraftions exprelfing thofe four contingencies for the fecond year 

^»"g — W~* — ^^^r-> __ 2atc ■ '^ -^ J fo^ 

the third year p^, ,,,, , ^^ >atid^, 

and ib on, the whole value of the given fum will be = 

S . d ^ be , md , nu . bd , S . a'' md ^ m . nd . me , S . a'" 
abcr 3366 abcr* 33 ^ ^ ^^^'^ 



-+^+'' +^+&c. which are=-i. X fl'+f::^+f:ifi:!+acc.+ 

3 %3 6 6 %abc r r* r' 



s xf:2:f+^+^+&c.+-Vx^+^^?+^ + &c. 

babe r r* r' babe r r r* 

<,±.x'i^+^^+^ +&C. From the demonftration of 

'^ yb( r r* r* 

the problem in my laft Paper * it appears, that the firft of 
thefe feries is - ?- x ^' ' ^^-^^^ - 1 x BC-ABC ; that the fe- 

3 >>* y 

-^ , . S ^ «.BK-ABK S ^m.PC-APC ^, • . 

cond feries is = g x — x ; that the 

* Sec PhiU Tranf. Vol. LZXIX. 

Vol. LXXXI. L 1 third 



250 ^^- Morgan on 



third icries is =» - x 7 r ^ ; and that the 



fourth fcries is= 5 xBC-ABC.-l x^l^LiZll^'. Thcfefc 
3 3' ^f 

veral expreffions being added together will be found =S into 



,^ ..FK-.AFK BK-ABK g .^_^^p^ ^^g^;-^ 
3r ^ * 2 0* 3r 

in> PC-.'^PC ja^ BT>^ABr , w. FT --APT 

This theorem gives the exaft value when either B or C are 
the oldeft of the three lives ; but when A is theoldeft, it will 
be neceffary to exchange the fymbols a\ a'\ a"\ &c. for 
tf— J, J-/, /-w, &c. and the fymbols w, », o^ &c. for 
cw", <r-7+7^f c-7+7^"?^^ &c. In this cafe the value 
of the given fum for the firft year will be founds— into 

aber 
ah isc , amc msc ohc . hsc' am/ , iwj^ >• i /- 

--- + — -Y~V + T~T T* for »he fccond year= 

' mtn""' '"'t ,*"t fite mst" mte" nse" , i»fe" w./ . mic' 
__into-- — + - - -g-+— --_ + _ ^+— - 

!:ff:+!!ff:. for the third year=-ij into !!L'-^'+f!f+'iL'-!:if:' . 
a » <»^' 2 a i a 6 ^ 

nut"' »W que" _ fit . V+f^' w . ^^c" 0, . 7^ lu .7^7' 

63 3 ~ a "*" a """1 + 5^ » 

«nd fo on for the remaining years of A's life. Hence the 

whole value of the given fum will be = — x— + i2f+!l!i4. &c» 

aa* r r* r^ 
a-^'^T + r'+rr + ^ec. + _X_+-+_+ &C. -_ ,t 



!^+!Li^-+&c. + J^x^ + 2¥:+«^'+ &c. +-1- X 



Survhdrjh^, 2^1 



!!ff:+-JLi4±£+&c,-l-xf!^'+«JLif:+fL;il'+&c.. ^ 



^atc r r* r^ 2a6cr 



ns/ ot .c' + c'' - ^ , S msc" nt . e' . out'" , ^^ S 

— + 1 +&C. +— -X + _ + -^j-+ &c. X— - X, 

^— +-—»-'— + &c. • . . The firft four fcries arc refpedively = 
— r- (or 1 '— + . • . The nrft term of 

the fifth leries, or — , is = 4" ^ --3 ^ i^\ the fecoud term 

' ' r fibr u0 age 



or —r -, is=i --— X — -— i^ f . . • . the third term, 

«■—=-, is^-— x---^ . — - — ;:; — ji-— • Therefore 

r^ abr^ op aft r* 

*liefumofthefifthandfixthfenesis?: _ !iii^pH!C^ _ ^ ^ 
?^'^''^^' - &c. :i ) - - X AB-A3C. In the fame manner the 
Seventh feries ^zy be found ?• ^ x AF - AFC - ^^ - 
"" • '^ +' &c» ; apd confequQDtly tdje fum of the fevcnth and 



babcr'^ ' 



eighth feries is • ^.iM^El+'-iB:^. Again, the ninth and 



tenth fencs may be founds ^- ( -g^j;^. ^^-i- 

^fecs)-- "*'^^,"^^^ ; and the eleventh and twelfth or two 



M A r ^ AB--ABC/ ntc' , uo.c'-^-cf' . - v , wi.l'N-PNC 

Jaft feries, ■'^^^:j-(+^^»+-5;^'H^c.=)4- ^^,, . 
If all thefc expreflions be added together, we ^^11 have the 

value of the given fum «■ S into -^ x '-^ — J^ AF + | AFC 

L 1 a ' + 



452 Mr. Morgan on 



it may be obferved, that the firft four feries are alfosE;. 
aud therefore if this value be fubftituted inftead of *^ ' "y , &c. 

2ab ' 

the general rule will become = E + S into - - x HB-HBC+ — 

** • 3 " 2* 

X B.>l -BiNL+^x PN -PNC Suppofing the three 

lives to be equal, the firft of thefe rules will becoroe=lil2E _ 

^__ ir 

b.cc y ~* "^ 6< "^ 6^r ^ *"■ 

O 6 . « . r ' jr ^J 

^i CC CCC » . CK-CCK «« . KK- CCK ^ . CT-CCf , 

6^^ : and alfo the rule denoting the value (whea 

; cither B or C are the eldeft of the three lives) will becomes 

CT-— CCT id ', 

•~y p^xTT-CTT. LetthisIaftexprciSonbecancd 

Q and compared with the firft of the preceding expreffioas. In 
thif cafe wc fliall have !+£C^cc+ac^_cc-ccc Q , 

^-5; ^=Q, from which) Q may be eafily founds 

S r^ 1 . V— CCC 

3 ^ '-? ! Agaio, let the iame ejcpreffioo, denoted 

by 



by 0^9 be compared with the fecond of the preceding expref- 
fions, and we (hall then have '^ElZ^ - ^ +"ELl££l£2 

rrQ, afid coirfequently Q= S x — :— * "^ as before * . • . • 

Now it is well known, that when the lives are all equal, the 
Talue of the reverfion muft be one third the difference betweea 
the perpetuity and the three Joint lives,, and therefore a denion- 
ilration arifes of the trulh of the whole folution. As a ftiUj 
further proof of this, the foregoing theorem may be imme- 
diately deduced from the feries themfclves : thus, the value of the 

givea fum for the firfl: year will in this cafe be»i '^/"r * ^^^ 
the fecond year it will be « ^-—^' I ^f ^^^ thirdyear it will be 

_Sjj^^ . Hence the value of the whole reverfion^ will bc=r' 

3^^^ 

^ ^ r -TTr-.— » "• ^""^ + 3-^*+.V + .v5 + &C. = . K] 

L ,CCC+^=:^ x^'^"^^ ... Q.E.b. 
r ^ i ^ 



]PROBLSMI£» 

To determine the value of a given fum, payable if A fhould 
be tht/ectaid that fails, of the three Uvea A,, B, and C«. 

SOLUTION. 

The fum S may be received in the firft year, provided either 

* Thh expreffioQ may alfo be obtained from either of the above general roles,, 
iodependeat of the two oUieFir ia Ukeinaiuier at in the folution Qi the fourth 
fsoblem. 



i^^ Mr. Morgan on 

of three events (hould happen; iftj if the three lives fllduW 
become exrinft, and A be the feCond that fails; 2dly, if A 
(hould die after B, and C live; and, jdly, if A (hould die 
after Ci and B live. But in the fecortd and following year«, 
the given fum may be received, provided either of (even events 
(hould happen* ift, If the three lives (hould fail in the year, 
A's life having been the fecond that failed, idly, If A only 
(hould die in the year, B having died before the beginning and 
C lived to the end of it. jdly. If A only (hould die in the 
year, C haiving died before the beginning ai:id B lived to the 
end of it, 4thly, If A (hould die after B in the year and C 
iive. 5thly, If A (hould die after C in the year aod B live, 
6thly, if A and C (hould both die in the year (A dying firft) 
and B*s life (hould have failed in one or other of the foregoing 
years ; and, 7thly, if A and B (hould both die in the year (A 
dying firft) and C's life (hould have failed in the foregoing 
years. From the feyeral expre(fi6ns denoting thefe contin- 
gencies the Wjhole value of the rever(ion may be found = 

± X £f + 4' + <^ + &c. + ± + i?+2;'+i2 + &c + 

iac r r* r' iac r r" r* 



S a'b , a"m . a"'«i . - , S «'« . «"» . a"'» , - 

2ah r r* r^ ^abe r >* ? 

The two firft of thefe -fcries areciD, . . the two nextsE . . . 
and it appears frpni the foly tion of the pi;eceding pra}>le<n that 
the four remaining feries exprefs double the value of the fum 
S, dq)en4ing oa thp PPWipg^iocy-of 4*# jJ/^Pg ftt;ft jC^^hw B 
or C are the oldcft of i:he ithcee 1^) wkh a negftCiy^ ^i« 



Survhorjbips, j.- 

The general .rule, therefore, in this cafe will become = D+ 
E-aM. 

But when A is the oldeft life, rccourfe muft be had, as 
in the (ccond part of the preceding problem, to different fym- 
bols, and the value of the reverfion will then be found = 

^ -7 •*•— -^T^ + ^^ ' + .J "^ r+ 7^ + - + ^*^- + 

-1. X "*'' 4. '""" U. ""'" JL Sf^n S V bi'f .mtc" Hue" ' . " 



Qbc r r' ' abc r r" ' ^* T^ 

^x---+— J-+— ,-+&c. + -x---+_^+&c.+ 






&c. -^x - + _+- + &C. + — X— + _+_+&€. Thelaft 

ai r f r^ Oh r r r^ 

two, aiid the firft ten feries are= — 2M, the eleventh and 
twelfth ferieaarerzD, and the thirteenth and fourteenth feries 
z=E ; confcquently the gei>eral rule becomes = D+E — 2M, as 
before. 
Suppofing the lives were all equal, the above expreiSon would 

be =5 — X r — I . V — CCC =* - x x 

^ y" 3 r 

V — 3CC — 2LCC, which is known from other principles ♦ to be 
the true value^ and therefore the invefttgation is right. As a 
further demonftrationi however, it may not be improper ta 

* Sec Phil. Tranf. Vol. LXXIX. 

obferve^ 



256 Mr. Morgan oji 

obfervet that this rule is immediately obtained from the dif- 
ferent fra&ions which exprefs the feveral contingencies in each 
year. For in this cafe, the value of S for the firft year becomes 

six 1 -^+21-, forthe fecondyear=:-rX ^ + -t 

r % cc ^ '' t cc cc <^ (^ 

and {o on for the other years. Thefe feries being added 
together will be found = — ^— + "i — + T~i + ^^^ "" 






S ^ r-i 



+ &c. = 3 xi:ilx V-3CC-aCCC Q. £• D. 



PROBLEM III« 

To determine the value of a given fura payable on the 
death of A, if his life fhould be the loft that fails of the three 
lives A, B, C. 

SOLUTION. 

The given fum can be received in the firil: year only upon 
the extindion of the three lives, A having died laft. In the 
feeond and following years it may be received provided either 
of four events (hould happen : ift, if ^11 the three lives (hould 
fail in the year, A dying lafl: ; 2dly, if A (hould die after C in 
the year, B having died in either of the foregoing jrears; 
3dly, if A fhould die after B in the year, C having died in 
either of the foregoing years ; 4thly, if only A fhould die in' 
the year, B and C having both died before the beginning of it. 
The value therefore of the reverfion (when B or C are older 

than 



Skrvhor/hips. • »5y 

th.nA)wllbe-lxl.t-l-+l,-+&c+p;.< -+ — +-^ 

'-J.X --:^+fi'+^^ + &c. - -i xf2+?::?+f^ + &c. -: 



When the life of A is the oldeft of the three lives, the fym- 
bols being changed as in the two preceding problertis, the value 

of the reverfion will become = - ^ ^ ^ +^ + ^ + &«• - 



^r-^^"-^ + ^- + SiX^+=^^"f' + *- + 




By the fecond part of the felution of the firft problem, the 
firft eight feries may be found a=M-E; and the lad two 

feries being eafily refolved into|-xlIi+'-~ + lZ? + &c. - 

s viEiJE?4.iHLfr±t£+ &c. --^xfHIif+iHi^E? 

+ &;c. arerrG-D. Hence the general rule, as in the former 
cafe, becomes =G + M - U + E. 
VoL.LXXXI. Mm When 



aijS Mr. MoRGAi^ on 

When the lives are all equal, the above expreffion will bcr 

changed into -xr-ix. V-C + -^ - V^CCr: 

'x -^^; or " one-third x\\t value of the abfolute reverfion- after 
3 

** the. extindtion of the longeft of the three lives.'* This is 
known from felf evident principles to be tl^ true value, and 
therefore the foregoing Iblution is correft. The farae rule may 
alfb be obtained immediately from the fcries ;* for the value in 

this cafe for the firft year will be=:-- x i -- +-_-^_ for 

•^ r ^ c cc 3^' 

the fecond Year=-T x-^ — — , h- +--1, and fo on for 

r y^ 3t^ cc c u c 

the remaining years. Hence the whole value o£ the reverfionj 

will bc=:- X L+ - X rrL==':il^ X l:^.... a E. D. 



r i 



P R O B L E M IV. 



To determine the value of a given fum payable on the ex^ 
tindion of the lives of A and' B, ihoald they be the fr/i that 
fail of the three lives Ay B, and CI 

S^ O- L U T I O' N^ 

The glv^en fum may be received in the firff year, either on. 
the extinction of the three livesy C having died laft: ; or on 
the extinction of only the two lives A and B, C having fur- 
vivcd the year. In the fecond and following years the given 
fum may be received, provided either of fix events fbould 
happen, ift, If the three lives fliould become extindl in the 
year, C having been the laft that failed. 2dly, If A only 

ftould 



Sufvhorjhtps. 255^ 

fliould die in the year, B having died before the beginning, and 
C lived to the end of tt. 3dly, If B only fliould die in the 
year, A having died before the beginning, and C lived to the 
^nd of it. 4thly, If A and B fliould both die in the year, 
and C fuwive it. . 5thly5 If C fliould die after A in the 
year, B having died in either of the foregoing years. 6thly, 
if C fliould die after B in the y«af, A having died in either 
of the foregoing years. The fraftions cfenoling thefe fe- 
veral contingencies being added together will be found =±' 

-^ X - +--i'-+ -T5— + &c. 4 K — +-- + __: + &c. - . 



^obc r r^ r^ ' Zubcr r r*^ 






3L ^'!iJI!£+^::!l^€^ ^ &CC.,- ^y^'i^^-'^-^^^+kz. 
The firft two feries are = D ; the third and fourth fcries are 5: 
£ X Bc^TaBC-^^^^^P^; the fifth and fixth feries arc= - 

y 6 . P C 

..BK-/VBK^m.eC-APC ^^ ^^^^^ ^^^ -^^^ f^^^^ ^ 

y \>br ^ 

g.FarAFC y.BT-ABT j ^j^^ ^^^^^ ^„j tenth fcrics = 
m^:pr^At>i- _ 2.iic-AB^ Hence the Whole value of the 

tbcr 3 

reverfion will be = D - ^ x ^-^^^^ + BKrAB^+ 1^ x ] 



BT-Atfi+ '"^^J^^'^ 



M m » "The 



26o Mr» MoieAK m 

The preceding theorem exprefles the value of the giveo 
fum whether C be the oldeft, or B oue of the two lives to bo 
furvived, and will therefore be fufficient in all cafes^ In order, 
however, ftili more fully to prove this, let A be luppofed the 
oldeft life, and inftead of i> - «, m — /;, « - o, &c. and <»', y, 
a"\ &c. let I/, b'\ b'"^ Sec, and fl^T, /^, t~u, &c. be 
fubftitoted; then will the value of the reverfiotv be found a 

^ r t t* i,b( r r »» 

s Mb' . dib" , nff" , - . s db .rt.y+b" . !r^ 

-— X -f.—.^.-^- + &c. + _— X — + . + &C. - 

babe r r* r* a^^r r r' 

X— + -^+-j- + &C. -r- X + ji— •(.&& + 

Let S denote the value of S on the contingency of Cs fur- 
viving B, and the general rule deduced from the preceding 

feries will become = S -5jJ:x^^^^^^^+ AK=rABE: + 

3 aa 

5gJ'xHC-.HBC-Hi^xAC:-.Aiic-?~xNC-iNlfiC+: 



^•^ TT Tunn .*• NT- NBT ,., 

— X Ai -AtJi + — , whtch appears to be exadly 

the fame rule with the foregoing, if the fymbols of A and B 
be only exchanged for each other. 
\i the three lives be of the fanae age, both thofe rules will 

feverally become = S into "^ xV-CC - - x K.K-CKK - 
a TT- 



Survhorj^fts, i^i 

*rT-CTY. The two ' expreffions - 2Lilp£E^+ ' ,< 
CT — CCT, by refolving them into their refpeftivc feries, will 
be foundc=^.I^ + -^ + T-^. + r^4^^ + ficc., and the two 

or 6^ 0^'A Ofc /* Oc /* 

«xpreuiOQS 7 — —x CK - CCK » -^ 2— — 

'^ 6irr c 6r 6cr 

T^+g^ + ^ + itc; hence the fum of thefe four expref- 
fions will be = '-r;^ — 9 and confequently the general rule 

in this cafe will be = 5-^~^ X V - 3CC -2CCC, which is 

kuown to denote the true value from other principles ♦. 

As a further proof of the accuracy of the preceding invefti- 
garion, it may not be improper to obferve, that this rule may 
be immediately obtained^ from the different fractions which 
cxprefs the value of the given fum in each year. For in this 

cafe the value of S in the firft year is=s — x- —2—+ i — in 

the fecond year =r - x-^-^-V-x + ^» and fo on in the 
Other yearSt which expreflions may be eafily found = 
5-^^xV^3CC-.2CCC. Q.E.D. 



PROBLEM V. 

To find the value of a given fum, payable on the death of 
A» if his life (hould be the^;^ ox fecond that fails of the three 
lives A, By and C. 

• Sec 07 Paper in the Phil. Tfanf. Vol. LXXIX. 

SOL V- 



262 ikfn McRGAK on 

SOLUTION. 

In the firft year the payment of the given fum depends 
upon either of four events, ift, That all the three lives (hall 
beconle extinft, the life of A having been the firft or fecond 
that failed. 2dly, That A and B (hail both die, and C live to 
the end of the year, 3dly, That A and C (hall both die, and 
B live to the end of the year. 4thly, That only A (hall die, 
and B and C both live to the end of the year. In the fecond 
and following years the payment of the given fum will depend 
upon either of eight events happening, ift, That all the 
three lives (hall drop in the. year, A having been the firft or 
(eeond that failed, adly. That G furvives, and only A and B 
die in the year, ^dly. That B furvives, and only A and C 
die in the year. 4thly, That both B andC furvive, and A only 
dies in the year. 5thly, That A dies in the year, B having 
died before the beginning, and C lived to the end of it. 6th!y, 
That A in like manner dies in the year, C having died before 
the beginning, and B lived to the end of it. ^thly, That C dies 
after A in the year, B's life having failed ineither of the preced- 
ing years. 8thly, That B dies after A in the year, Cs life having 
ftiled in either of the precedingyears. The fractions denoting thefe 

^ , . • s ~c 7\1 a"' . e I 
feveral contmgencies are = — x — + — j— H j- + &c. + 



— X — + — — +— r + ^^- + nX— + —r-+—r + &c. + 



a'm . (*"n . fl'"tf . , S ^^i/hc . a''md 



babe r r* H babe r r t^ 






Thi« 



Tilts general rule gives the true value whether the life of A 
be older or younger than both or either of tlie lives of B and 
C. When the three lives are of equal age, the value of S for 

the firft vear will be= -x - + ^ " — » ^^^ ^^^ fecond yearir 
- X— , r + — » and fo on for the other years. Hence 

the whole value in this cafe will be = ^'1""' X 2V--^CirccC, 

which expreflion may alfb be derived from the general rule juft 
given above, or D+ E - M. 

The folution of this problem may alfo be obtained either 
froni the firft and fecond, or from the third problems. In the 
one cafe the value of S is evidently equal to iht Jum of the 
two values determined by the two firft-mentioned problems, 
or D + E-2M + M=:D + E-M. And in the other cafe its 
value is equal to the difference between the abfolute value of 
the reverfion after A'( = G) and its value depending upon the 
contingency that A fhall be the laft life that fhall fall, whlcli 
being=:G + M — iJ + r. by the third problem, it follows, that 
the general rule on this fuppofitioi>- will he alfo = D-i-E - M- 
C^E. D. 



P R O B L E M VI* 

To find the value of a s;iven fum payal)Te on the death of A, 
ihould his life be \ht fcond or third that (hall fail of the three 
lives A, B,.and C 

SOLUTION,. 

The payment of the given fum in the firft year will depend 

upon the contingency of either of three events, ift. That 

n all 



thu. Mr. Morgan on 

all the three lives fhall become extiuft, A having been the fe» 
cond or third that has failed. 2dly, That A (hall die after 
B, and C live to the end of the year, 3dly, That A ftiall die 
after C, and B live to the end of the year. In the fecond and 
follov^ring years the given fum will become payable, provided 
either of eight events fliould happen, ift, If all the three 
lives ihould fail in the year, A having been the fecond 
or third that died. 2dly, If A Ibould die after B in the 
year, and C live to the end of it. jdly, If A ihould 
die after C in the year, and B live to the end of it. 4thlyy If 
A and C (hould both die in the year, B having died before the 
beginning of it. fthly, If A and B (hould both die in the 
year, C having died before the beginning of it. 6thly, If A 
only (hould die in the year, the lives of B and C having be- 
come extind in either of the preceding years. 7thly, If A 
(hould die in the year, B having died before the beginning, and 
C lived to the end of it. 8thly, if A (hould die in the year, 
C having died before the beginning, and B lived to the end of 
it. Hence the whole value of therever(km will be foundry 

S «' . ^" , «"' . n,^ S ^ a be ^ J'md , d'^nt , - 

4xf2l^ + -^"+-^'+ &C. .^^._^.^£«. £^/ g^^_ 
taifc r r r* o^^f r t* r* 

s ^ -w^-:^L'+ f:'x+ &c. =G . M, 

^abc r r T^ 

This rule is corred in all cafes ; but when the three lives 
are equal it becomes more (imple, and is = — *^'"' x 



2V-3C-CCC; which expreffion may likewiie be obtained 
immediately from the feries given above. 

The folution of this problem, like that of the foiegoing 
oue, may alfo be derived from the (irft three problems; for the 

value 



SurH)POdrJhips% 265 

value of S is either equal to the difference hetween the abfolute 
value of the reverfiou after the death of A and its value de- 
pending on the contingency that A (hall be the firji that fails 
(found by Prob. k), or it is equal to thc^yZoa of the two values 
depending on the contingencies that A (hall be the fecund or 
third that fails (found by Prob. 2. and 3.)« In both cafes the 
general rule is s: G ^ M. Q. E. D* 



PROBLEM V12» 

To find the value of a given fum payable on the death of A, 
(hould his life be the S^Jt or U^ that fails of the three lives 

BOLUTtOK* 

In order to receive the given fum in the firflyear, it is necef« 
fary that either of four events (hould happen, ift^ That all 
the rhree lives (hould fiul, A having been the firft or third that 
died, zdly, That B (hoold die after A, and C live, jdly^ 
That C (hould die after A, and B live. 4thly, That A only 
ihould die, and B and G both live. In the fecond and follow- 
ing years the given fum may be received, provided either of 
feven events (hould happen, ift, If the three lives (hould 
fail, A having been the firft or laft that died. 2d]y, if B 
ihould die after A in the year, and C live to the end of it* 
3dly, If C (hould die after A in the year, and B live to the 
end of it. 4th]y, If A only (hould die in the year, and B and 
C both live to the end of it. 5thly, If A's life (hould fail 
after that of B in the year, C*s life having failed before the be- 
ginning of it. 6thly, If A ihould fail after C in the year, 
B having failed before the beginning of it. 7thly, If h only 

V01-. LXXXI. N n (hould 



266 Mr. Morgan m 

(hould die in the year, B and C having died in either of the 
preceding years. From the fradions denoting thefe feveral 
contingencies the whole value of the reverfion will be founds 



•'"- 



« r r- r* %ac r r* H 



iittt: 



— X — + — +— f- + &C. .X + -T- + —r + &c- "• 

— rX— +-r+-T" + ^^» + :rT X — + -r- H — t" + «c. + 

4xf:2f+f:j/+9r+&c.=G-^+E+2M. 

This general theorem will give the exa6l value in all cafes; 
but when the lives are equal, it is rendered more iimple, by 
fubftituting the feveral values of G, D, £, and M, and will 

then become = ^-—ll x 2V-3C-3CC+2CCC i which expref- 

fion may alfo be derived in this particular cafe from the dif- 
ferent feries denoting the value of S in each yean 

The folution of this, like thofe of the two preceding pro- 
blems, may likewife be obtained by the adiftance of the firft 
three problems^ For the value of this contingent reverfion is 
either equal to the fum of the two values of S payable on the 
death of A, if his life (hould be the firft» or if it fliould be 
the laft that fails (found by Prob* u and 3.), or it is equal to 
the difference between the value of the abfolute reverfion after 
A*s death, and the value of the contingent reverfion after A*$ 
death, provided he fhould be the fecond that fails of the thret 
lives (found by Prob. a.). In both cafts the general rule be* 
comes;2G-D+li + aM. Q. E. D^ 

mo 



Survivor/hips. 267 



PROBLEM VIII. 

To find the value of a given fum payable on the death of 
A or B, (hould either of them be the firjl that (hall fail of the 
threp lives A, B, and C. 

SOLUTION. 

In each year the payment of the given Aim will depend upon 
either of fix events. ifl> If the three lives fhould fail in the 
year, A or B having died firft. zdly,- if A and B (hould die iu 
the year, and A live, jdly, If C (hould die after A in the 
year, and B live. 4thly, If C fhould die after B in the year, 
and A live. 5thly, If A only (hould die in the year, 
and B and C both live. 6thly, If B only (honld die in the' 
year, and A and C both live. The fradions denoting thefe 

feveral contmgencies are ■ -21x1^1+ , / +-7- + ^^' "" 



^f f 



Sg^ — +— + — + ^'- ^piXy +-pr+-;^+ &c. + 
babe a ir t* qm 






+5S^"r-+-"7' + &c - S into p X -^ 4: 

iyv xmi P.FC-AFC , a.7^.BC-ABC , w.t'C-APC rf . 
BK-ABK— — gj 4. ^ + 5p- X 

BT ~ ABT-h " • ^^J^^^ +S (S denoting the value of S on 

the contingency of C*8 furviving B, as in Prob. 4.) 

Nna The 



263 Mf. MoRGASr on 

The above rule gives the exad value when C is the oWcft 
of the three lives. But if A be the oldeft, the fymbols 
muft b6 changed as in fome of the foregoing problems^ 
and the value in this cafe will be exprefled bj the feries 

»ix^+=f:+2C + &c. - » xe=;+2;'+!!C+ &c. - 

y^c r r* r* babe r >* r^ 

S bsc^ , mi<f' , nuc"'-. - ^ S ^ mc' , if/*'' , •«/'' . - . 
X— + J-.+-— + &C. - —-X +_-+__+ &C.+ 

— • ■ if I 1 n II 

S . ab , mi tit ^ 5 wi , w/ , ^« k «, 

41^ . r r* r' ab r r^ H 



— X — + r^— + &€• + — X _ + — -jX_ ^&c. From 

tfif r r* abc r r* ^ 

thefe feveral feries, the general rule expreflihg the value 
of the reveriion will be found m S into • 



-I .v-AB • 



__^^_^^^ . ______ '' !f *' 

. HF-MFd" , HB-HBC g . AF-AFC , 2 ♦ r-'-. t . A B-ABC . . 
Z + i 6^ " + "p: +. 

w.AP-AFC S BN-bNC w.FN-PNC 
5^^ ^ 3ar a + 3 • 

When the lives are all equal, the firft rule becomes a 

^TT . V-CC I a . r^T . CC-CCC , «» . KKIIcKK . K . CK—CCK 

ar ' y • . 6« • 6c "" 

i.'cTrca'_^LWgg ^^j thefecond rule-^HLIES 

> g . r>-i .CC-CCC ««,KKI^CKK ^> KC-CCK rf. CT-CGr 



r^ . V-CC 



+ — ' • — -f In the one cafe the four laft fraSIohs are=r 

; and id the other cafe tfaofe fra£lions are= --[ 



f— I V — cc 

' ; therefore, in both ea&s the general mle beeoffle» 

3r .!*y-CC^> wWch is knowA to be the true value 

from 



2 ,S . r_ J 



Si^vhbrjhtpu 26^ 

from felf-evidcnl prmciplcs* This expreffion may alfb be 
immediately derived from the different fraflioDS which detiole 
the value of S in each year. For. ta the firft year thefe fraftions 

will be reduced to — x — , irl the fecond year to- 

3 '^ ^''^ I ^ 

^ X "i^, in the third year to — x ^ -Z^* and fo on in the 
other years* Hence the whole valud of the reverfion will> as 



2 . S . r - I 



above, be « '^^'' ;'"^ x V -cCC. Q. E» D *. 



P R O B L A M IX» 

To dettjfttitne the value of a giveti fiiiA pi^abld on the death 
of A ot % fhould ^//^^^ df them be tht/ns/td that fails of the 
three lives A, B, and C» 

SeLUTION. 

The payment of the given fum in the firf! year will depend 
upon either of foiir events happening, ift. That the three 
lives ihoxAd fail^ A of ^ having been the fecond that failed* 
2d]y, That A fiieuld die after C, and B live. 3dly, That B 
(hould die after C^ and A live. 4thly9 That A and B (hould 
both die, and C live* In the fecond and following years the 
giveti fum will become payable, provided either of eleven 
events ihould happen, ift. If the three lives (hould drop in 
the year, A or B havidg been the fecond that failed, idly. If 
A ihould die after C in the year, arid B live. 3dljr, If B 
ihould die after C in the yeat, and A live. 4thly, If A and B 

* ] de not IcQo^ that any fohitioii hai been attempted before, either of thi»or 
9I the two folbwing problem* 

ihould 



270 Mr. Morgan on 

(hould both die in the year, and C live. 5thl)r, if B onljr 
fhould die in the year, A having died before the beginning, and 
C lived to the end of it. 6thly, If A only (hoXild die in the 
year, B having died before the beginning, and C lived to the 
end of it. 7thly, If C fliould die after A in the year, B hav- 
ing died in either of the foregoing years. Sthly, If C (hould 
die after B in the year, A having died in either of the 
foregoing years, pthly^ If A and B (hould both die in the 
year, C having died in either of the preceding years. lothly^ 
If B only (hould die in the year, C having died before the 
beginning, and A lived to the end of it. And, laftly, if A 
only (hould die in the year, C having died before the begin- 
ning, and B lived to the end of it. The feveral fractions de- 
noting thefe contingencies in each year being added together will 

become == -r ^ — + ^r— +&c. - -r x — + r^^ — + &c. 



* abc r r* ahc r \r'' ^ 



j^xtfi'+^+''4:+ &c. +i-x!2ff:+»4:+'4: + &c. - 

^bc r r M ^ahc r r* r* 



S b—m.c . m—n.d , 




—-5 — , S ma' n.a''\'a" , - S hi' , w.^/' + n" . -^ ,1 



4. x!f:+^+::f; + &c. + 1 xizfLi+!!i=^+r^+ &c. +; 

ab r r*" r* b r r" r^ 

S 17 dtp IP'' r~ S dp ea" fa'" 7 r r% 

^xtf.+?l.+'l^+ &c. +-±.x^+fl.yij.+ &c. Let Q 

denote the value of S by the firft rule in the eighth problem^ 

aod the firft ten feries will be=Sj^2Q« The four next feries 

3 arc 



Surwowrjblpt. 271 

area *'^''^'"';^"^^ ; and the two laft feries are=D; the 
whole value of the reverfion, therefore (when C is the oldeft 
of the three lives), is=5jLl:ii^IEZ!+D+S-2Q. 

When A is the oldeft of the three lives, the different feries, by 
changing the fymbols, as in fome of the foregoing problems, will 

become= ~x h • |.&c, — - x — + -_ + &c. - 

^abc r r r^ ^abc r r* /* * 

-T- X — + -r +-T- + &c. - -7- >f — + — +— r + &C' - 



— X — + JL-_ + &c. + — X + J + &C. + 



X + __+__+ &C. -— X _+__ + __-+ &C. + 

S ^b—m m—n u- » » S 7—m. m-nt n—t.u . « 
_ X + — ,- +-.- + &C.--r X + J— + — +&C. 



+4- »«^^^^^^ + -^^^^^^'+&c. Let Q reprefent the value of S 

ab r r * 

by the fecond rule in the eighth problem, n and A the values 
of the fame fum on the contingency of B's dying after C, 
and on the contingency of A*s dyit>g after C reipedlively ♦ ; then 

will the general rule in this cafe become = '^""'^^ — - - — ^ 



r-i.iV-B-A 



- 2Q- n+ A, or, becaufe D+2 are = ^^— n + A +, 

• See zny 3d Frob. in PhU. Tranf. Vol. LXXVUIt 
t Sec 1B7 2d aad 3d Frob. VoL LXZVIil. 



v,yz Mt. MoBOAxr on 

atwillbea *^"^'^ ^ — + D + 2-aQ, as above^ 

When the lives are equals the rule may b« found either Im« 
mediately from the feries, or from the foregoing expreifiou^i rs 
aS . r— 1 



3^ 



XV-3CC-2CCC. Q,E. D, 



PROBLEM X. 



To find the value of a given fum payable on the deceafe of 
B or C, fliould eiiber of them be the lajl that ^ils of the three 
lives At B) and C 

SOLUTION* 

The fum S can be received in the firft year only on the cx- 
tinftioii of the three lives, reftrained to the contingency of 
A*s life having been the firft or fecoqd that failed. In the 
fecond and following years it may be received piovided either 
of fix events (hould happen, ift, If the three Jives fhouldfiiil 
in the year, A having been the firfi: or fecond that died, sdly. 
If B and C fhould both die in the year, A having died before 
the beginning of it* 3dly, If C only (hould die in the year, 
A and B having died in either of the preceding years. 4thly, 
If B only fhould die in the year, A and C having died in either 
of the preceding ycara. 5thly, If B (hould die after A in the 
year, C having died before the beginning of it. 6thly> If C 
fhould die after A in the year, B having died before the 
beginning of it. From the fradions expreffing thefc feveral 
contingencies, the whole value of tlie reverfioo will be founds 

2S ^ mda' , ne.a'^a" . ^^^ S ^ bca' ^ md Ta'-^^ , ^7^' 



Survivcffiips. 27J, 



babe r y* ' r» ' babe r ' r^ ' r^ 



s xilll + ll^ + &c. - J-xJ^+i^pl + &c. + 

^abr r ^ r'^ 2,abr r r* 



X + z_-f &c. X— +-^ — 3; + &c., ana 



therefore the general rule (when either B or C are the oldeft 

of the three lives) will be = S into^^-^^=i^'/?::i-'^^-^ x 
^ y_ 3^ 

g . FK-^ AFK BK ^ ABK ^ m PC--APC i/.Pi-A»T g.A'C -AFL 



d BT-ABT jg, F-AF r-i , B--AB m.P-AP ic,K~AK 
"*" 6rr *" a* *" ar "" zbr "*" 2* 



r-i . c-AC ^. T-AT J ^^ ^gj^^^ thefirft five ext)reffionsare«, 



7X 2€r 



^ — — — '— M, and the fix remaining onesaR+W) it 



will be=.^ "'";^'"^^+R+W-^M, 

^6en A is the cUefi of the three lives^ the fame general rule 
may be obtained. In this cafe, by exchanging the fymbols, 

the difierent feries will become=:^^xl-^ + '^''^^''' +&c. ■>; 



tote r r* 3«*»' ][ ]_ 

4.x^:Li^+"i.:^^+&c.+'X:^+C+ J+&C. -' 
V0L.LXXXI, Oo S 



2«4 ^' MOEGAK M 






+ 71 h &C. +T-T-X — + J J- &c. - 

f Outer r r* • 



3^ 



X + — -J [-&C.+— X — + J—A^Scc. » S into 



/ 



2.r^l . AB^ABC _^^ g ^ it. HF-HFC ,, AF- AFC I "* ' ™-™^ 

^ X MB NBC 1 ^' PN^="^N ic m.AP-APc ;37 , vIIc , 



3*^'' 



2* • b/Ir 



1 — —-. + — . In order to 

r 2,r 2a 2ar 

fret the fame general rule as that given above in the cafe of B 
or C*s being the oldeft of the three lives, it is to be obfervcd, 
that the firft five exprcffions, by the fecond part of the folution 

of Prob, I. appear to bcg ^'^^ ' M + E. And (fup- 

pofing r to reprefent the value of S on the contingency of A's 
dying after C) that the laft three expreffions appear to be 
^ . P^ TT-i.A^AC g^^ g i5;.R+^"ELiEA!^ and W muft 



be='^""''^^^^^'^'^^-r; therefore, the fum of the above 



expreffions may be eafily found zz ' "^"^ ' ' ^ + R + W 

-M. 
U the three lives be of equal age, the value of the rever- 



aS . r - I 



fion will ben — ^ x V -L. This expreffion may be dc* 

lived either from the foregoing general rule, or immediately 

from 



Survhorjhips. ^ 275 

from the different feries, and is known to be accurately true 
from felf-evident principles. Q. £. D« 



I have now given general rules for determining the values of 
reverfions depending upon three lives in every cafe which, as 
far as I can difcover, will admit of an exaSi folution. The 
remaining cafes, which are nearly equal in number to thofe I 
have inveftigated, involve a contingency for which it appears 
very difficult to find fuch a general expreflion as (hall not 
.reuder the rules much too complicated and laborious. The 
contingency to which I refer is that of one lifers failing after 
another in any given time. The fractions exprefling this proba- 
bility are every year increafing, fo that the value of the rever- 
{lou mud be reprefented by as many feries at leaft as are equal 
to the difference between the age of one of the lives, and that 
of the oldeft life in the table of obfervations* I have indeed fo 
far fucceeded in the method of approximation as that the rcver- 
fion-may be generally afcertained within about; ^.'^th part of it^ 
exaflt value ; but I (hall not trouble the Royal Society at 
prefent with thefe inveftigations. 

The 34th, 35th, and 36th problems in Mn Simpson's Se- 
lect Exercifes involve this contingency, and, by the affiftance 
of M. DE Moivre's hypothefis, admit of an eafy fbtution* 
But fuch is the fallacy of this hypothefis, that It renders Mr^ 
Simpson's conclufions obvioufly wrong, though his realbning 
is perfeflly corred : for it cannot furely be an equal chance in: 
all €afes that one life (hall die after another. In the fliort 
term of a finglp year the chances are indeed fb nearly equal,, 
that it would be wrong to perplex the folution by attempting 

O o 2 greater 



a^6 Mr. Morgan on 

greater accuracy. But when the number of years, and the 
difference between the ages of the two lives are, confiderable, 
thofe chances muft vary in proportion ; and, therefore, unlefs 
the contingency is blended with another which (hall very much 
diminifh the probability of the event, the folution, by thus 
indifcrimiuately fuppofing the chances to be equal, muft be 
rendered extremely inaccurate. In Mr. Simpson's 36th pro-^ 
blem the folution by this means appears to be abfurd : for, in 
the particular cafe in which C is the oldeft of the three lives, 

C — AC 

the value of the reverfionary annuity becomes = ; that 

4S, the value of an annuity in this cafe during the life of C 
after B and A, provided A dies firft, is the iame whatever be 
the age of B ; for no mention is made of his life in the fore- 
going expreffion. It (hould be obferved, however, that the 
rule itfelf is ftridtly true, and that the error arifes from Mr. 
Simpson's having been mifled by the hypothefis in determin- 
ing the probability of B's dying after A in his inveftigation of 
the 34th problem, which is applied to the folution of this 
problem *. 

I have declined giving fpecimens of the different values of 
the reverdons as deduced from the foregoing rules and thofe 
which have been hitherto publifhed, not only from an appre- 
heniion of becoming tedious, but alfb from the convidion 
that at prefent they are unneceffary ; thofe which I have for- 
merly given being, I think, fuflScient to prove the inaccuracy 
of M. DE MoivRs*s hypqthefis. In thofe inflances in which I 
have compared fome of the foregoing rules with the approxi- 

* It if proper to obfenre, that I have followed Mr. SiMPsoN*f method of 
detemifaiitg this contiogeocjr in the ajd, sytb, aStb, and a^tli rn>hle8Bi in mjr 
Ti-eatiie oo ^enuitiei. 

4 nations 



Survhorjhips. 277 

xnations now In ufe, I have invariably found the latter to be 
erroneous ; nay, in fome cafes, the values were almofl twice 
as great a^they ought to have been. This is particularly true 
when one of the lives is very young, and both or either of the 
other lives are very old. In reverfions of this kind I believe 
that this is generally the ca(e, and that it feldom happens that 
the ages of the three lives are nearly equal. The approxima- 
tions therefore can hardly ever be ufed ^yith fafety, and it will 
certainly be moft prudent not to have recourfe to them wheti 
the coxrtdi values can be obtained. Should the difficulties 
attending the folution of the remaining problems which in- 
volve three lives be furmounted (and the talk may not perhaps 
be impoflible), the hypothefis of an equal decrement of life, as 
far as it relates to any ufeful purpofe in the doctrine of annui- 
ties, may then be totally abandoned. Or fhould it even be 
found impracticable to deduce folutions of thofe problems 
which are ftriftly and accurately true ; yet, I am fatisfied from 
my own experience that fuch near approximations may be pro- 
cured as to render this hypothefis equally unnece0ary. 




[ «78 1 



XVIIT. JbJlraSi of a Regifter of the Barometer^ Thermsme^ 
tery and Rain, at Lyndon in Rutland ; by Tiiomas Barker, 
jE/^. ; mth the Rain in Surrey tfWHampfhirc ; for the Tear 
1 790. Communicated by Thomas White, £/^. F.RJSL 

Read June 2, 1791. 



Barometer. 



Thermometer. 



Rain. 



Higheftj 



Loweft. 



Mean. 



In the Houl'e. 
High. Low. Mean 



Abroad. 
High.|Low. Mean 



Lyndon 



Surrey. 

S. La III' 

bctb. 



Hampfiiire> 



Sel 
bourn. 



fybdi 

Inch. 
1,72 

0,43 
0,38 

3.66 
0,55 

1.7' 

1,97 
0,51 

I.J5 
5." 
3.38 



Jan. 

Feb. 

Mar. 

Apr. 

May 

June 

July 



Aug 



Sept. 

oa. 

Nov. 
Dec. 



Morn. 

Aftcrn. 

Morn. 

Aftcrn. 

Morn. 

Aftern. 

Morn. 

Aftcrn, 

Morn. 

Aftcrn, 

Morn. 

Aftcrn, 

Morn. 

Aftcrn. 

Morn. 

Aftern. 

Morn. 

Aftern, 

Morn. 

Aftern. 

Morn. 

Aftern, 

Morn. 

Aftern, 



Inches. 
29>97 
30,05 

30,13 

29.85 
29,80 

29,86 

29,73 
29,68 

29,9s 
29,81 
39,88 
29,87 



Inches. 
28,48 

29,20 

29,31 

29,01 

28,93 

28,98 

29,90 

29,17 

28,88 

28,89 

a8,49 

a8,32 



Inches. 
29,55 
29,71 

29,77 
29,42 

29,45 
29,56 

29,35 
29,49 
29,53 
29,43 
29,35 
29,33 



49 
49 
48 

49i 

SOi 

5» 

51 

52f 

58 

S9i 

7« 

75i 

64 

66 

66 

67§ 

62 

61 

57 

59 

49i 

49 J 

46 

47 



36 
40 

41 
42J 

44 
40 

41 

501 

51 

54i 

551 

57 
58 

56 

57 

52 

53 

45i 

45i 

37l 

38 

36 

36 



41 

4ii 

43i 

44i 

46 

47 

44 

45 

54 

55 

59, 
6o| 

60 

61 

60J 

62 

55i 

57 

52 

S3 

44 

45 
40 

40i 



SO§ 
S2| 
48 

57 

43i 

60 

49i 
61 

57 
72 
65i 

85 
62 

78I 
62i 
80 

59l 

72§ 

55 

65 

48 

SH 

48 

49 



26i 

34i 

30 

4oi 

3' 

42§ 

32 

'\ 
43i 

52i 

48I 

56 

49{ 

62 

49 
57 
42 

n^ 

46 
30 
32 

25i 
3» 



37 

41 

38i 

47 

39§ 

52 
38i 

49 

49I 

61 

55i 

67I 

57 
69 

69 

491 
61 

45i 

55 

40 

44i 

38i 

43 



Inch. 
1,871 

0,236 

0,259 

0,676 

2,911 

2,385 
2,246 

^735 
1,566 
0,991 

3,145 
3,608 



Inch. 
i»49 
0,20 

0,24 

2,54 
3,70 
0,64 
2,42 
2,26 
0,52 
1,72 

3»40 
3.»8 



Inch. 
^99 
0,49 
0,45 
3,64 
4,38 
o,>3 
3.24 

2,30 
0,66 
2,10 

6,95 
5.94 



Inches 21,629 



22,31 



32,27 



n,05j 



The 



A/r. Bai^ker^s Regtfter^ &ۥ 279 

The thermometer abroad being broken in December^ that 
month is defedive in that article. 

THE winter proved a remarkably open one; no froft of 
two whole days together, nor any fnow ; fo that there were 
young artichokes in the garden all winter, where they were 
Ihort and among the leaves ; and the fecond crop of figs, which, 
are generally killed in winter, efcaped this year, and ripened in 
the fummer, but did not grow large. It was l^ud there were 
young hares in winter, and birds* eggs laid, fome of which 
were perhaps hatched. Several people faid they faw a covey of 
young partridges near Oakham in February; bii't I cannot 
affirm it, for others fufpedled fome miftake. January was 
Ihowery and mild, but often windy ; as the days grew longer, 
it became dryer, finer, and forward. Afwarmof beesrofc and 
icttled at Tixover, March 2. ; but it was rather a (hifting of 
their hive for want, than a regular fwarm, which could not 
have been bred fo early. The owner, having a deferted hive 
with combs and honey in it, put them into that, where they 
lived, and grew ftrong in the fummer. The forwardnefs of the 
feafon continued till the N.E. winds of March made it colder 
and morefrofty ; the growth of all things was then flopped, 
and the firft fortnight in April was feverer than any part of 
the winter, with the only fnow this feafon. 

The feed time was dry, and in general good ; bqt, for want 
of froft in the winter, the ground ploughed ftiff, and required 
a great deal of working ; and the feafon continued dry and 
backward till after the middle of May, when rain and warmet 
weather made every thing grow as faft as they were flow be- 
fore« The fummer was chiefly cloudy and windy, and after 

7 the 



/ 



i86 /Mr.'BktXVK^I^egtJter^ &c* 

the middle of May very (howery and cool, except fbme few 
violent hot days ; and a very grotving feafon, fo that grounds 
laid at the end of May had good crops of hay on them, whlcli 
in general was well got, for the rains in this country were not 
great, though frequent ; and fo much land was laid late, and 
{o much over-eaten grafs cut, that there was hardly ever more 
good hay made than there was this year. The harveft alfo 
was fliowery, yet not fo much but that thofe who were not too 
hafty got it well, and it was plentiful, though very rank, 
and pretty much laid, yielding well to the acre, though not to 
the flaiL 

The autumn was dryer, fine, and pleafant, fo that the 
ground began to burn. The wheat feed time was 'remarkably 
good ; for it was dry at firft for fowing the clay land ; then rala 
came in good time to bring it up, and that made the ground moift 
for £>wing the dry fields. There was a good deal of rain at times 
in November, .yet fo much fine weather between, that it was 
pleafant and not dirty ; but moft part of December and Ja* 
nuary was uncommonly ftormy and uncertain weather, chang* 
ing fometimes two or three times a day ; fevere ftorms, much 
rain, great floods, and remarkable thunder, on feveraldi^rent 
^ys, and in many difibrent phces. Near a fortnight^s froft at 
Chriftmas, with dear weather at firft, but afterward one great 
rain, and feveral lefler, which yet did not take away thefraf^ 
:till January the 6ttu 



Cbalk 



Cbalk found in a new place. 

There IS a great deal of chalky ground iii the fouthera part 
of England ; I think it jbegins at the fca ia Devonfliire, and 
one vein of it runs all lalong the fouthern counties to Dover^ 
Aopther vein parts off from that about Reading in Berkfliir^, 
goes by Dunftable, Baldock, and Gogmagog Hills, and (q pa 
to the fea in Norfolk s the whole eroding the kingdom in a Y.. 
Along thefe two diflridt^ it is almpft all chalk to a gre^f depth 
in the ground; Jbuto^jt of |hep9 chalk is feldom^ found. J be-* 
lieve it maj be ni§t wkh in many places in the countries 
betWiCfia tiysCe twp diftri^^ and fometimes dqep in thp grouody 
where it does not cooi? ^ to the furface ; but beyond the 
northern limits of them, which are at Wantage in Berklhire, 
and over the river from Shillingford in Oxfordffiire, and at 
Maddingley by Cambridge, chalk is hardly any where to be 
found; no where in any confiderable quantity, unlefs it be 
much farther north, in the wolds of Yorkfliire, beyond Pock- 
lington toward Scarborough. 

I did not know till lately that we had any chalk nearer us 
than Maddingley ; but fcveral years ago, the people of Rid- 
lington in Rutland, digging for ilone to mend the roads, met 
with a bed of chalk ; at which they were much furprized, 
and did not know what it was, having never feen a chalk pit 
before. After I had heard of it, I went to examine the place, 
and found it a regular chalk pit, with rows of flints lying in 
it as is ufual in the fouth of England. The chalk is not foft 
like that they write with, but very much like that they dig 
about Baldock ; nor are the flints fo black as thofe in the fouth 
of England, but veined, of a light-coloured flint, and white. 

Vol. LXXXI. P p fomc 



282 Mr.BAKi.EK*sjiccounej &c. 

fome parts much mixed with chalk ; and arc brokeiij not whole 
ones. They may have dug the pit fix yards long and two 
deep ; but how far the chalk reaches I do not know. The 
ground about it has plainly been formerly dug, perhaps thirty 
yards fquare, but completely turfed over again, with the fame 
ftrong turf as the reft of the clofe, which is rich pafture land, 

and feeds oxen for Smithfield market, not like the fhort grafs 

on the chalky downs. 

, Riding laft autumn along the turnpike road near Stukeley ia 

Huntingdonfliire, I faw a little patch of chalk, a few yards 

long, in a bank which had been dug away by the road fide; 

fo that though we did not know there was any chalk at all in 

this country, and there certainly is very little, yet here arc 

now two places where it has been met with. 




t »83 3 



XIX. Defcnption of a Jtmple Micrometer for meafuring fmall 
Angles with the Telefcope. By Mr. Tiberius Cavallo, 
F. R. S. 



Read June 2, 1791. 

THE various telcfpopical micrometers, or machines which 
have been conftrufted for the meafurement of fmall 
angles, may be divided into two clafles ; namely, thofe which 
have not, and thofe which have, fome movement amongft 
their parts. The micrometers of the former fort confift moftly 
of fine wires, or hairs, varioufly difpofed, and fituated within 
the telefcope, juft where the image of the obje<9: is formed. 
In order to determine an angle with thofe micrometers, a good 
deal of calculation is generally required. The micrometers of 
the other fort, of which there is a great variety ; fome being 
made with moveable parallel wires, others with prifms, others 
again with a combination of lenfes, and fb on ; are more or 
lefs fubjedl to feveral inconveniences; the principal of which 
are the following. ift, I'heir motions generally depend 
upon the a£tion of a fcrew, and of courfe the imper- 
fections of its threads, and the greater or lefs quantity of loft 
motion, which is obfervable in moving a fcrew, efpecially 
when fmall, occafion a confiderable error in the menfuration of 
angles, idly, Their complication and bulk renders them dif- 
ficultly applicable to a variety of telefcopes, efpecially to the 

P p 2 pocket 



284 -^^- Cavai.x.o^s De/tription of 

pocket ones, 5dly, ^ They do not nkzhtt the angle without 
fome lofs of time, which is neceflary to turn the fcrew, or to 
move fome other mechanifm. 4thly, and laftly. They are 
confiderably expenfive, fo that fome of theni coft even more 
than a tolerably good telefcope. - 

After having had long in view the conftrudion of a micro- 
meter, which might be in part at leaft, if not intirely, free from 
all thofe objections ; and, after various attempts, I at laft foc- 
ceeded with a (imple contrivance, which, after repeated trials, 
has beeh found to anfwer the defired end, not only from my 
own experience, but from that alfo of feveral friends, to whom 
it has been communicated. 

This micrometer, in (hort, coniifts of a thin and narrow 
flip of mother of pearl finely divided, and iituated in the focus 
of the eye-glafs of a telefcope, juft where the image of the 
object is formed. It is immaterial whether the telefcope be a 
refra6lor or a refleftor, provided the eye-glafs be a convex lens, 
and not a concave one, as in the Galilean conftrudlion. 

Thfe fimpleft way of fixing it is to ftick it upon the dia* 
phragm, which generally ftands within the tube, and in the 
focus of the eye-glafs. When thus fixed, if you look through 
the eye-glafs, the divifions of the micrometrical fcale will ap-* 
' pear very diftinft, unlefs the diaphragm is not exaftly in the 
focus ; in which cafe the micrometrical fcale muft be placed 
exactly in the focus of the eye-glafs, either by pufliing the 
diaphragm backwards or forwards, when that is pra<fticable ; 
or elfe the fcale may be eafily removed from one or the other 
furface of the diaphragm by the interpofition of a circular 
piece of paper or card, or by a bit of wax. This conftruftioo 
is fully fufficient when the telefcope is always to be ufed by 
the fame perfon ; but when different perfons are to ufe it, then 
.3 «^« 



ajmple Micrometer. 285 

the diaphragm, ivbich/, fvpports the micrometer, muft be rpn- 
flruffced fo as to be eafiljr mared backwards or forwards^ though 
that motion needs not be greater than about a tenth or mi 
eighth of an inch* This is neceflarj, becauie the. diiknc^ of 
the focus of the fame kns appears different to the eyes ipfidij- 
ferent perfons, and tben^e, whoever ia going to u£b t))citele* 
fcope for the menfuratiou of any angle, muft firft of aU.ut^ 
(cxtw the tube^ which contains the eye-glafs and micro^afietier, 
irom the reft of the teiefcope, a(mi$ looking through /the eyto* 
glafsi muft place the mierorteiter ,whQre the divifions of it' may 
appear quite diftind: to his eye. 

In cafe that any perfon ihould not like to fee always the 
micrometer in the field of the teiefcope, then the microme- 
trical fcale, infiead of being fixed to the diaphragm, may be 
fitted to a circular perforated plate of brafs, wood, or even 
paper, which may be occafionally placed upon the fald dia- 
phragm. 

I have made feverai experiments to determine the moft ufe- 
ful fubftance for this micrometer. Glafs, which I had fuc- 
cefsfully applied for a fimilar purpofe to the compound micro- 
fcope, feemed at firft to be the moft promifing ; but it was at 
laft rejected after feverai trials : for the divifions upon it gene- 
rally are either too fine to be perceived, or too rough ; and 
though with proper care and attention the divi(ions may be 
proportioned to the fight, yet the thicknefs of the glafs itfelf 
obftru6:s in fome mcafure the diftin<Sl view of the object. 
Ivory, horn, and wood, were found ufelefs for the conftruc- 
tion of this micrometer, on account of their bending, fwei* 
ling, and con trailing very eafily ; whereas mother of pearl is 
a very fteady fubftance, the divifions upon it may be marked 



2S6 Mr. Cavallo's Defcripiion of 

veryeafily, and, wheii it is made as thin as common writing 

paper, it has a very ufeful degree of tranfparency. 

Tab. VIII. fig. I. exhibits this micrometer fcale, but 
(hews it four times larger than the real (ize of one, which 
I have adapted to a three-feet achromatic telefcope, that 
magnifies about 84 times. It is fomething lefs than the 
.14th part of an inch broad ; its thicknefs is equal to that of 
common writing paper; and the length of it is determined 
by the aperture of the diaphragm, which limits the field of 
the. teleicope. The divilions upon it are the 2oodths of an 
incli, which reach from one edge of the fcale to about the 
middle of it, excepting every fifth and tenth divifion, which 
are longer. The divided edge of it paffes through the center 
of the field of view, though this is not a neceffary precaution 
in the conftruftion of this micrometer. Two divifions of the 
above defcribed fcale in my telefcope are very nearly equal to 
one minute; and as a quarter of one of thofe divifions may be 
very well diftinguiflied by eftimation, therefore an angle of 
one-eighth part of a minute, or of 7''!, may be meafured 
with it. 

When a telefcope magnifies more, the divifions of the mi- 
crometer muft be more minute ; and I find, that when the 
focus of the eye-glafs of the telefcope is fliorter than half an 
inch, the micrometer may be divided with the 50odths of an 
inch ; by means of which, and the telefcope magnifying about 
200 times, one rfiay eafily and accurately meafure an angle 
fmaller than half a fecond. 

On the other hand, when the telefcope does not magnify 
above 30 times, the divifions need not be fo minute : for iu- 
ftance, in one of Dollond's pocket telefcopes, which when 
drawn out for ufe, is about 14 inches long, a micrometer with 

the 



afimpie Micrometer. 287 

the hundredths of an inch is quite fuSicient, and one of its 
divifions is equal to little lefs than three minutes, fo that air 
angle of a minute may be meafured by it. 

In looking through a telefcope, furnifhed with fuch a micro* 
meter, the field of view appears divided by the micrometer 
fcale, the breadth of which occupies about one-feventh part of 
the aperture, and as the fcale is femitran (parent, that part of 
the objeft, which happens to be behind it, may be difcerned 
fufficiently well to afcertain the divifion, and even the quarter 
of a divifion, with which its borders coincide. Fig. 2. (hews 
the appearance of the field of my telefcope with the micro- 
meter, when diredted to the title page of the Philofophical 
Tranfadlions, wherein one may obferve that the thicknefs of 
the letter C is equal to three-fourths of a divifion, the dia* 
meter of the O is equal to three divifions, and fo on. 

At firfl view one is apt to imagine that it is difficult to 
count the divifions which may happen to cover or to meafure 
an obje£l: ; but upon trial it will be found, that this is readily 
performed; and even people, who have never been ufed to 
obferVe with the telefcope, foon learn to meafure very quickly 
and accurately with this micrometer; for, fince every fifth and 
tenth divifion is longer than the reft, one foon acquires the 
habit of faying five, ten, fifteen, and then, by adding the 
other divifions lefs than five, completes the reckoning. Even 
with a telefcope, which has no ftand, if the objed end of it 
be refted againft a fteady place, and the other end be held by 
the hand near the eye of the obferver, an objedt may be miea-» 
furcd with accuracy fufficient for feveral purpofes, as for the 
eftimation of fmall diftances, for determining the height of a 
houfe, &c. 

After 



288 Mr. Cav ALLOCS Dejcription of 

AittT having conftrufled and adapted this micrometer to the 
tekfcope, it is then neceffary to afcertain the value of the divi-» 
fions. It is hardly necellary to raention in this place, that 
though thofe divifions meafure the chords of the angles, and 
not the angles or arches themfelves^ and the chords are oot as 
the arches, yet it has been (hewn by all the trigonometrical 
writers, that in fmall angles the chords, arches, iioes, and 
tangents, follow the fame proportion fo very nearly, that the 
very minute difference may be fafely negleded : fo that if one 
divifion of this micrometer is equal to one minute, we may 
fafely conclude, that two divifions are equal to two minutes, 
three divifions to three minutes, and fo on. There are various 
methods of afcertaining the value of the divifions of fuch a mi* 
crometer, they being the very fame that are ufed for afcertaifiing 
the value of the divifions in other micronMters. Such are the 
pafTage of an equatorial ftar over a certain number of divifions 
in a certain time, the meafuring of the diameter of the fun, 
by computation from the focal diflance of the object, and other 
lenfes of the telefcope, the lafl of which, however, is fubjeft 
to feveral inaccuracies ; but as they are well known to afiro- 
nomical perfons, and have been defcribed iii many books, need 
not be farther noticed in this Paper. However, for the fake of 
workmen and other perfons not converfant in aftronomy, I 
fhall defcribe an eaiy and accurate method of afcertaining the 
value of the divifions of the micrometer. 

Mark upon a wall, or other place, the length of {vsi inches, 
which may be done by making two dots or lines fix inches 
afunder, or by fixing a fix-inch ruler upon a ftand; then place 
the telefcope before it fb that the ruler or fix-inch length may 
be at right angles with the direction of the telefcope, and jufl 
57 feet 3i inches diflant from the obje£t-glafs of the telefcope : I 
this done, look through- the telefcope at the ruler or other 

exteofion 



• pnple Micrometer. i^ 

^xteniioii of fix inches, and obferve how mdny idivifions of 
the microtneter are equal to it, and that fame number c^ divi^ 
iions is equ^i to half a degree, or 30^ ; and this is all that 
needs be done for the required determination ; the reafon of 
which is, becaufe an exteniion of fix inches fubtends an angle 
of 30' at the diftance of 57 feet 3I inches, as m^y be cafily 
calculated by the rules of plane trigonometry, 
. In one of Dollond's 14-inch pocket telefcopea> if the divi- 
iions of the micrometer be the hundredths of an inch^ 1 1 i of 
thofe divifions will be found equal to ^p\ or 33 to a degree. 

When this value has been once afcertained, dny other angle 
tneafured by any other number of divifions is determined by 
the rule of three* Thus, fuppoft that the diameter of the 
fun, feen thrcHigh the fame telefcope^ be found equal to li 
divifions, fay as ii| divifions are to 36 minutes, fo are 12 

divifions to ^ii^^j 3I^3• which is the required diameter 

of the fun. 

Not withftan ding the facility of this calculation, a fcale may 
be made anfwerUig to the divifions of a micrometer, which 
will (hew the angle correfponding to any number of divifions 
to mere infpe£lion. Thus, for the above-mentipned fmall 
telefcope the fcale is rcprefented in fig* 3. AB is a line drawn 
at pleafure ; it is then divided into 23 equal parts, and tho/e 
divifions, which Veprefent the divifions of the micrometer that 
are equal to one decree, are marked on one fide of iti The 
line then is divided again into 6q equal parts, which are marked 
on the other fide of it ; and thefe divifions reprefcnt the mi- 
nutes which correfpond to the divifions of the microtneter i 
thus the figure (hews, that fix divifions of the micrometer are 
equal to 15! minutes, iii divifions are nearly equal to 29 

Vol* LXXXL Q ^ .. minutes^ 



M^o Mr. CavAllo^s Defcriptlon of 

minutes, &c. What has been faid of minutes may be faidof 

feconds alfo, when the fcale is to be applied to a large 

teiefcope. 

Thus far this micrometer, and its general ufe, have been 
fufficicntly defcribed, and mathematical perfons may ealily 
apply it to the various purpofes to which micrometers have 
been found fubfervient. But as the fimpliciry, eheapnefs, and 
at the fame time the accuracy of this contrivance, may render 
the ufe of it much more general than that of any other mr- 
crometer ; and I may venture to fay, that it will be found 
very ufeful in the army, and amongft fea-faring people, for the 
determination of diihnces, heights, &c. ; I (hall therefore fub- 
jolu fome praftical rulesto render this micrometer ufefut to per- 
sons unacquainted with trigonometry and the ufe of logarithms* 

Problem I^ The angle, not exceeding one degree, which 
is fubtended by an extenfion of one foot being, given, to find 
its diftance from the place of obfervation. 

N. B.. This extenfion of one foot,^^ or any other -which may 
be oijsntioned hereaftei:, muft be perpendicular to the dire^oa 
of the teiefcope through which it is ohferved;. The diilanccs 
are reckoned from the objed-glafs of the teiefcope, and the 
anfwers obtained by the rules of this problem, though not 
exactly true,, are however fb little different from the truth, 
that the difference feldbm amounts to more than two or three 
inches, which may be fafely negleded^ 

Rule I • If the angb be expreffed in minutes, fay, as the 
given angle is to 60, fa is 687,55 to a £3urth proportional, 
which gives the aufwer in inches. 

2. If the angle be exprei&d in feconds, iay, a& the given 
angle is to 360.0, fo is 687,55 to a fourth proportional, whicH 
eitprcfiTes the anfwer v^ inchest 

7 3-K 



ajimple Micrometer. api 

3. If the angle be exprelTed in minutes and feconds, turn 

it all into fcconds^ and proceed as above. 

Example. At what diftance is a globe of one foot in diame* 

ter when it fubtends an angle of two feconds ? 

2 : 3600 :: 687,55 ; 3 ^^^ 7.^*^ =: 1237590 inches, or 

103 1 32 J feet, which is the anfwer required. 

This calculation may be ihortened ; for (ince two of the 
three proportionals are fixed» their produfl: in the firft cafe is 
41253, and in the other two cafes is 24751 So ; fo that in the 
£rft cafe, viz, when the angle is expreiled in minutes, you 
need only divide 41253 by the given angle; and in the other 
two cafes, viz. when the angle is expreffed in feconds, divide 
2475 1 80 by the given angle, and the quotient in either cafe is 
the anfwer in inches^ 

Prx>blem IT. The angle, not exceeding one degree, which is 
fubtended by any known extenfion, being given, to find its 
diftance from the place of obfervation. 

Rule. Proceed as if the extenfion were of one foot by Pro- 
blem L and call the anfwer B; then, if the extenfion in 
queftioQ .be expreffed in inches, fay, as 12 inches are to that 
extenfion, fo is B to a fourth proportional, which is the anfwer 
in inches ; but if the extenfion in queflion be expreffed in feet^ 
then you need only multiply it by B, and the produ£fc is the 
anfwer in inches. 

Example. At what diftance is a man, fix feet bigb^ when 
he appears to fubtend an angle of 30^'. 

By Problem I. if the man were one foot high, the diftance 
would be 8 2506 inches ; but as he is fix feet high, therefore mul- 
tiply 82506 by 6, and the produd gives the required diftance, 
which is 495036 inches, or 41^53 ^^^^ 

Q q 2 For 



2jZ Mn Cavallo's Dejcriptm of - 

For greater convcnicncy, efpecially in travelling, cr in fijch 
ctrcumftances in which one has not the opportunity of making 
even the eafy calculations req^uired in thofe problems, I have 
calculated the following two tables ; the firft of which (hews 
the diftance anfwering to any angle, from one minute to one 
degree, which is fubtended by an extenfioh of one foot ; and 
the fecond table (hews the diftance anfwering to any angle from 
one minute to one degree, which is fubtended by a man, the 
height of which has been called an extenfion of (iic feet ; be« 
caufe, at a mean, fuch is the height of a man when drefled 
with hat and (hoes on. Thefe tables may be tranfcribed on a 
card, and may be had always ready with a pocket teiefcope 
furnifhcd vvith a micrometer. Their ufe is evidently to afcer- . 
tain diftanccs without any calculation ; and they are calculated 
only to minutes, becaufe with a pocket teiefcope and micro- 
meter it is not poffible to meafure an angle more accurately 
than to a minute. * 

Thus, if one wants to meafure the cxtenfion of a ftrect,; 
let a foot ruler be placed at the end of the ftreet ; meafure the 
angular appearaiKe of it, which fuppofe to be 3V, and in the 
table you will have the required diftance againft 36^ which is- 
95 1 feet. Thus alfo a man, who appears to be 49^ high, is 
at the diftance of 42 1 feet*. 

T- CAVALLO^ 

Wells-fifoct, 
Maya6, 1791. 



Angles 



0jimpk Micrometer^ 



*9S 



An{;Te8 fubtended by an exteniion of one foot at differeotf 

didances^ 





Diftances 




DiHances 


Aogles. 


in feet. 


Angles. 


in feet. 


Min. t 


3437.7 


Mia. 31 


110,9 


2 


1 7 18.9 


32 


107,4 


3 


1145.9 


33 


104,2 


4 


859.4 


34 


101,1 


5 


687.S 


3^ 


98,2 


b 


S72.9 


36 


95.S 


7 


491. 1 


37 


92.9 


8 


429.7 


38 


90.4 


9 


382.0 


39 


88,1 


lO 


.343.7 


40 


85,9 


II 


3»2.S 


41 


83,8 


12 


286.S 


42 


81,8 


13 


264,4 


43 


79.9 


J4 


245.5 


44 


78, r 


IS 


229,2 


45 


76.4 


i6 


214,8 


46 


74.7 


17 


202,2 


^l 


73.5 


i8 


191,0 


48 


71,6 


19 


180,9 
i7».8 


49 


70.1 


20 


5° 


68,7 


21 


162,7 


51 


67.4 


22 


iS6.» 


52 


66,t 


23 


149.4 


S3 


64,8 


24 


»43.a 


54 


63.6 


II 


137.S 


SS- 


62,5, 


132,2 


S6 


61,4 


;i 


127.3 


% 


60,3 


122,7 


S9i2 


29 
90 


»i8,S 
114,6 


S 


S8,2 ^ 
.57,3. 



Aoglesp 



m 



Mr. Cav ALLOCS Defcriptiort^ tic. 



Angles fubtendcd by an extenfion of fix feet at difi^erent 

diflances. 





Diftances 




Diftances 


Angles. 


in feet. 


Angles. 


io feet. 


Min. I 


20626.8 


Min. 31 


665,4 


2 


I0?i3. 
6875,4 


32 


644,5 


3 


33 


625. 


4 


5*56,5 


34 


606,6 


5 


4"5,2 


P 


589,3 


6 


3437.7 


572^ 


7 

8 


2946,6 
2578.2 


% 


557,5 
542,8 


9 


2291,8 


39 


528,9 


lO 


2062,6 


40 


5«5,6 


II 


*^7|'« 


41 


503,1 


12 


.718,8 


42 


49*.« 


»3 


1586,7 


43 


479.7" 


»4 


«473.3 


44 


468.8 


«5 


1375- 


% 


458,4 


i6 


1289,1 


448,4 


W 


1213,3 


47 


438,9 


"45.9 


48 


429,7 


«9 


1085,6 


49 


421. 


ao 


1031,4 


SO 


412,5 


21 


982,2 


5» 


404,4 


22 


937.6 


52 


396.7 
389,2 


43 


£96,8 


53 


24 


«59.4 


54 


381,9 


^f 


«a5. 


55 


368,*3 


793.3 


56 


27 


763.9 
736,6 


5Z 


361,9 
355.6 


28 


58 


' 29 


711,3 


^9 


349,6 


3° 


«87,5 


60 1 343.7 1 



<f1ib 



1 



PhiloAlhans. Vol LHP. Tab. VUL £, ^4, 




S3civ4?^ .<•. 



[ *9S } 



XX. ^ new Method of tnve/figating the Sums of Infinite Series^ 
By the Rev. Samuel Vince, J. M. F. R. S. 



Read June Zf I79t* 

THE fummation of infinite ieries Is a fubjed, not only of 
curious fpeculationy but alfo of the greateft importance 
in the various branches of mathematics and philoibphy ; ia 
confequence of which it has always claimed a very confiderable 
ihare of attentioa from the moft celebrated mathematicians. 
I fhall therefore make no^ apology for offering, ta the public 
the following new and very expeditious method, by which we 
may obtain the fums of a great variety of ferics, moft of which 
have never before, been treated ofl As the fununation depends- 
on the fums of the reciprocals of the powers of the natural 
numbers^ tables of fuch films are ^ven as far as the 40th 
power to twelve places of decimals, by which the fums of 
the feries will be found tvue to ten or eleven places ; and if 
greater accuracy were required (which is a cafe that can very 
rarely happen) it might eaiily be obtained by continuing the 
tables. The firft and third columns (hew the fums, and the 
fecond and fourth the powers correfpondmg^ 



TABLE 



296 



Mr. ViNCB on the Sums 



1" A B L E L 



Sum of -^ 4- *^, + -^ + &c. 4id infinitum. 
2" 3« ^« 



Sum 


II 


Sum 




A 91,644934066848 


2 


W = ,000000238450 


22 


B =,202056903159 


3 


X =,0000001 ^9219 


23 


C =,082323233711 


4 


Y =,006009059608 


24 


D =,036927755107 


5 


Z =,000000029803 


25 


E =*»©' 734306 1 984 


6 


A' = ,0000000 1 490 1 


26 


F =,008349277387 


7 


B^ = ,000000007450 


27 


G =,004077356198 . 


8 


C = ,000000003725 


28 


H =,002008392826 


9 


D' = ,00000000 1 863 


29 


1 =,000994575128 


10 


E' = ,00000000093 1 


30 


K =,000494188604 


If 


F' = ,000000000465 


3» 


L. = ,00024608-6553 


12 


G' at ,000000000233 


32 


M s» ,000 1 227 13347 


13 


H'= ,0000000001 16 


33 


N =,000061248x35 


^4 


V =,000000000058 


34 


=,000030588236 


IS 


K' = ,0000000^ 0029 


SS 


P =,000015282259 


i6 


U =s ,ooooo©ooooi5 


36 


<^j= ,0000076371 9^ 


'7 


M' » ,000000000007 


32 


R =,000003817292 


iZ 


N'=, 000000000004 3S 


S «s ,000001 908 21 2 


19 


O' = ,000O0O0CO002 


39 


T =,000000953961 


20 


P' =,000000000001 


40 


V =,000000476932 


21 







TABLE 



if Infiniie Series, 



297 



TABLE . ir. 



Sum of i- - - +— -r — +&C. fid infinitum. 



Sum 


II 


Sum 


II 


a =* 9177532966576 


2 


w =,000000238386 


22 


b =^1098457322630 


3 


;e =,000000119199 


23 


c =,052967170503 


4 


y =,000000059602 


24 


d =,027880229587 


5 


z =,000000029801 


25 


e =,014448908703 


6 


of =,000000014901 


26 


f =,007406180072 


0m 

1 


3^ =,000000007450 


^Z 


g =,003766998147 


s 


c' =3,000000003725 


38 


h =,001905702459 


9 


^f =,000000001863 


29 


/ = ,0009 6049 2 403 


10 


«' =,000600000931 


30 


k =,000482856502 


II 


f =,000000000465 


3» 


/ =,000242314856 


12 


^'' =,000000000233 


32 


m =,000121457237 


13 


i6' =,000000000116 


33 


n =,000060829654 


U 


if =,000000000058 


34 


=,000030448787 


IS 


^' =,000000000029 


35 


p =,000015235790 


16 


/' =,000000000015 


36 


q =,000007621708 


17 


m' = ,000000000007 


37 


r = ,000003 8 1 2 1 30 


18 


n' =,000000000004 


38 


J =,000001906491 


»9 


0' =,000000000002 


39 


/ = ,000000953389 


20 


^' =,000000000001 


40 


V =,000000476742 


21 







Vol. LXXXI. 



Rr 



TABLE 



2gt 



Mr. ViNCB «|d* Sitms 



T A B L E HI; 



Sum of -^ + ~ + ri. + &«. actlnknittm* 

a* 4" 6' 



Sum 


II 


Sum 


II 


M' =,41.1233516712 
F/^ =,i f 02571 12895 
C^ =,067645202107 
D'' =,032403992347 
E'^ =,015895985344 
F''^ =^007877728730 
C =^003922 1 77 173 
H<' =^001957047643 
r =,000977533765 
K^:' =,000488522553 
\J^ = ,000244200705 
M'^ =,000122085292 
N^^ =,000061038895 
O'^ =,000030518512 
P^^ =,000015259024 
Q^^ =,000007629452 
R^^ =,000003814712 
S^^ », 00000 1907352 
T'^ =,000000953675 
V^^ =,000000476837 


2 

3 
4 

S 
6 

7 
8 

9 

10 

II 

12 

^3 
14 

'5 
16 

17 

18 

^9 
20 

21 


W^'' = »oooooo2384i9 
X^^ = ,000000 1 1 9 209 
Y'^ =^000000059605 
7J^ =^000000029801- 
Af^^ =, 0000000 H901 
B^^^ =,000000007450 
C^^ = ,000000003725 
D'^'^ - ^00000000 1 863 
E^^''. =^00000000093 1 
F'"' -^0600000004615 
Q^^^ = ,000000000233 
JAf^^ = ,000000000 1 J 6 
F''' =,000000000058 
K^''^ = ,000000000029 
U^^ =^000000000015 
M^^^ = ,000000000007 
N^''^ = ,000000000004 
0^^^ = ,000000000002 
^^^ =,000000000001 


2i-- 

24 

25 
26 

2$ 

30 
31 

3* 

33 
34 

36 

3^ 
39 
40 



TA»LE 



tf InJinite'Strks, 



X9f 



TABLE IV. 



Sum of — + JL + 1 + &c. <w^ ittfiniium, 
3" S" 7' 



Sum 


II 


Sum 


It 


V' =,233700550136- 

^' '-.o5«79979®»64 
c =,0146780316^4- 
^^ —,004523761760 
*" =,001447076640 
/" =,000471548657 
^' =,000155 1790*5 
^" =,000051345183 
i" = ,0000 1 704 1362 
*" =,000005666051 
/'' =,000001885848 
iw" =,000000628055 


"■2 

3 

4 

. 5 
6 

I 

9 
10 

II 

12 

'3 


«'' =,000000209240 
0^' = ,0000000 69724 

/: =,000000023234 

q^' =,000000007744 
r^^ Fi ^00000000258 1 
s'' = ,000000000864 
/"' =,000000000286 
v"' =,000000000095 
w^' =,000000000032 
•' =,000000000011 
y =,000000000004 

55^^ =,000000000001 


14 

«5 
16 

17 
.8 

«9 
20 

21 

22 

23 

24 

^5. 



FRCP. I. 



To Jind the fum of the fumt of the reciprocal fquares^ cuhes^ 

&c. &c. ad infinitum. 

By divfion =^ — =-t+ t +4 +&c. ad inf\ hence if wc 

X— IXX * « 4f 

make each of thefe terms the general term of a feries^ and 

write 2, a, 49 ice. ad inf. for x, we have .-i- + H + 

' ^ ^ ^ I . i 2.33.4 

&c.=»(Tablei.)A + B + C+D + &c.; but -I- + -i- + -L. + 
dtQ. ad inf.zzzi ; hence A+B + C + D-K&c. tf^^»/. = i. 



Rra 



As 



3QO Mr. Vivcn on the Sums 

As — ==-i- - 4- + r - -T +&C* ^^ ^V- 5 we have, by the 

*X*+i x^ x' ^ x^ ^ ■ -^ 

fame method of proceeding, A - B + C - D + &c. ad inf. — \ ; 
coufequently A + C + E + &c. = J, and B + D + F + &c- = i. 

Becaufer=J— = -V + -3 +~4 +*^- ^^ ^V- J ^^ ^^^ ^ ^e 
x—\y.x XXX 

write 2, 4, 6, &c., then will 1 b — z + ^c- = (Tab. 

3) A^^ + B^^ + C^ + D^^ + &c.; but -i. + -^ + -i- + &e.=. 

hyp. log. 2 ; h^iice A"' + W + C^ + D'' + &c. = hyp. log. 2. 
If in the fame expreffioii we write 3, 5, 7, &c. for x^ thea 

J. + .J« + ^ + &c. = (Tab. 4.) a''+b'' + c'' + &cQ.\ but 
2.34-56.7 ^ ^ ^ 

-J-+-^ + 7i- + &c.= i -hyp. log. 2; hence a'^ + l/'+c'^ 
2 . 3 4-5 6.7. ^r o 

+ &c. = I — hyp* log. 2. — Hence from either of thefc two laft 
cafes, we have a very expeditious method of finding the hyjv 
log, 2. 



? R o F. ir,^ 
To find the fum of the infinite feries whofe general term is 



mxdzn 



]5ydivinon-i- = .'-.=P-^-^-!!l.^— + &c. ad iufi 

mx dzn mx m x m^x^ nrx^ 

hence, if — ^ — be made the general term of a feries, and for 

X we write 2, 3, 4, &c., its fum will be equal to the fums of 
another fet of feriefes, whofe terms are the powers of the 
reciprocals of the natural numbers refpeitively multiplied 

into 



of h^mte Series^ joj 

into—, * — f ~^% &c.; hence the fum of each of thefe feries 

m m m^ 

beuig knpwn from the tables, the fum of the given feries \yijl 
be found. 

Ex. I . Let -r — be the general term ; now — i- =: 1 — I + 
-^ — -J- + &c. ; hence if for x we write 2, 3, 4, &c, we have 
r+,7;+f, + o7; + &^- = A-C + E-G+&c. = (bj Tab. I.) 

5 xp 17 20 . ^ "* f 

,576674037469. 

Ex, 2. Let-^ be the general term; then, by the fame 

method of proceeding, i- + i-4-i. + — + &c. =A+C + E + 

3 o 15 ^4 

&c. = (by.Prop. i.) - • 

Cor. Becaufe l- + ±+^+&c.= I xi+i+r+&c.= (as 

I + - + g +&C. is the reciprocal of the figurative numbers of 

the fecond order") \ x 2 = i ; therefore - 4.i- + J. 4. &c. = - , 
^^ 4 3 IS 35 a 

Alfo, as ~-=;^ +;^ + ^+&c. ; if we write 2, 4, 6, &c. for 

:c, we havei + — + -+&c.= (by Tab. 3.) A'' + C+E'' + 
3 15 35 ^ 3j^-r-r 

&c. = i ; but, by Prop, i . A'' + B'' + C' + D'' + &c. = hyp. log. 
z ; hence B'' + D" + F" + &c. = - ^ + hyp. log. 2. : 
Ex. 3. Let the general tetm be -ji-^ =~ +-i +^5 +&c, Aad, 

by writing 2, 3, 4, &c. for *, we have - + \ + r- + &c. = 

B+E + H+&C. = ,221689395104.. 

Ex. 



302 Mr^ ViNCB on the Sums 

Ex* 4. Let the general term be — i — = ~ + •^ + -—+ &c.| 

and, by writing 3, _3> 4, &c. for.;v, &c wc have JL + — + -rt + &c, 
^ ** •^ 40 241 700 

i-C+ ?G + -iL + &c.«,028385252D5z. 

Ex. «• To find the fum of the ferie* i - JL + JL --L + &c. 

•> 9 26 65 1*24 

If we write 2, —3,41 -5, &c. forje, the general term will 

— 5, &c. for x^ the feriefesof which -^ , .^ , &c. are tfcie ge- 
neral terms, will be alternately + an^ *- 9. and therefore their 
fums will be found in Tab. a. and the feriefes of which 

4-9 -^9 &c. are the general terms will have their terms all +9 

and therefore their fums will be found in Tab. i. Hence 
the fum required :=i i + b + o+ &c. -E-L-R— &c. = 
^oSz8oo93i$03. 

PROP. III. 

To find the fum of the fums of the reciprocals of. the odd 
powers in Tab. z. 

By divifion r — I — =-t + t + "* + "T +&c« J hence by writ- 
ing 2, —3, 49 — 5f &c, for if, the fums of the feriefes of which 
^9 4« ^^ ^^^ ^^ general terms, may be fouud by Tab. 2. 

and the other fums by Tab. i . ; hence -^ — h — ^ + -^ + &c 

1.23.45.6 

= A + C + E + &c + ^ + ^+/+&c.; but _i-+-JU+-ix + 

* • a 3 '4 5 • ^ 

&c. 



*f Infinite Series, ^x 

&c. = — - + 2 hyp. logi 2 ; and by" Prop. r. A + C + E +&c.=: 

^ ; hence ^+</+/+&c.= -5+1 hyp. log. a. ' 

PROP. IV. • 

To find the /urn of the infinite feries whofe general term is 

■ . 

By divifion — — p^ — I— =p — ^ — + — — =?= &:c. ad inf.z 

^i* db/i. mjc. ^ m X t/i^x^ 

hence the fum of 'the feries of which — ;; — is the general' tertii, 

mx'±.n 

is found as in Prop. 2. Here r muft be greater than j at leaft 
by 2, otherwife the fum will be infinite. 

Ex. I. Let the general term be --f— =i — 1 +-1 _ &;c^ / 

hence if for x we write 2, 2, 4, &c. we have ^ + i-+il + 

•^ 17 «2 257 ^ 

&c. = A- E + I-N+&C. =,538527924723. — If for x we 
write 2, 4, 6, &c. we get ^^^.^^+ J^ + &c. = A^^-E^^ + P 
,-N'' + &c. = ,396257616555.. 
Ex. 2. Let the general term be — ^^ — = -L + — -^4. JL 4. &c. ; 

hence if we write 2, 2, 4, &c. for ^, we have — + i. + -i. + &c. = 
•^ ^ 2j 80. 191 

I A+ iD+-G+&c. =,219238483448. 

By this propoiition we may find the fum of any feries whofe 
general term is ^^ ^ ^ — ^i? — JLi: ; for this refolves itfelf into 



mx zhn 



•-; — ^9 , &c. &c., the fum of each of which feries is 

mx'^:^n mx'^ztm 

& found 



304 JWr- ViNCE on the Sums 

found by this propoiition. Now the j-f-ith differences of the 
numerators of this general term are = o, and therefore it com- 
prehends all feries under fuch circumftances. For example, let 

the oiven feries be — + i^ + — +:^4- Here the third dif- 
*^ 17 b2 257 626 

ferences of the numerators = o ; to find therefore the general 
expreflion for the numerator, aflume ^at^+^^c-]-^ for it ; and, 
by writing 2, 3, 4, for x, we have 4J+2^4"^ = 4j 9^+3^+- 
— r«2 13. 16^+4^+^ ==26 ; hence ^ = 2, ^=^ — 1, r= —2; 
apd as Xha denominator is manifeflly ;c^4~'> ^^^ general term 
will bc ^^ 7^""^ = -^ JL -i- each of which being 

made the general term of a feries, their fum will be found to 
be refpedively 1,077055849446^ 0,194173022145, and 
^^^S^9SS^S933'^'^ hence the fum of the given feries is 
0,725927667969. 

If s be negative, the general term becomes r: — \r[ 






:&C^ 



Ex. I. To find the fum of — i-- ? — + — ^ &c. 

1 . .2 . 3 2.3.4 3-4.5 

ad inf. Here the general term is r =:r=r = — ==1 = 

;j + ^ + 77+&c.; hence, by writing 2, -3, 4, -5, &c. for 



Xj we hav6 the futn = ^4-^+/+ ^c. = (b^ Prop. 3.) -^ 
^ +2 hyp. log. 2. 



4 



If , ^ \ be the general term it refolves itfelf into 

x-^l x;ir'x x-f i .^ 

4+ 4 + 4+^^-5 confequentljr the" fum of — \ ?^ 



+ 



+— -^T &c. = - ^ - i-4-2 hyp. log. 2. In like manner the 

fun of \ 1— + — i &c. « - ^-. i/ - 5 J, 

I .'-i' . 3 2 .3^.4 3-45.5 4 ~ 

2 hyp. log, 2. Thus we may proceed as far as we pleafe by 
adding two powers to the middle term; and hence this remark- 
able property of the {eriefes, that the difference of the'fums of 
the leriefes where the middle term is x^ x\ x\ &c. is ^ ^9 f^ 
&c. refpeftively. 

Ex. 2. In like manner if the general term be 
and we write 2, 3, 4, &c. for x^ we have 



r .1 



* • 2^ • 3 2 • 3^ • S 
+ — L_ -+-&C. =D4-F+H4-&c. «« (by Prop. i.)I - B. 

3 • 4 • S 4 

Hence alfo - — 5^-, + ^ !, . + &c. = -^ - B - D ; and ib on as 

1.2.3 2 • 3 • 4 4 

before. 
If the general term be under the form - ^ ^ „^ , it 

will be ' naoft convenient to refolve it thus : hy divifion 

JL=1 -.t^+ll*^ See. =t= --C=; hence =±=—L= ==, 



X 



X « ;r-f m x • 4r-f-m 



x + m X x^ x' ' ^n x.x + m * *' «"• 

where the (ign on the left hand will be -j- or — according as n 
is even or odd, and the number of terms on the right 19 ^n. 

Now the fum of the feries whofe general term is — :2=«f 18 

X . x+m 

well knowny and the fums of the othec are found from the 

tables. 

Ex. I. To find the futn of -t^+t^ +-r^ + &c» aJinf. 

a -3 3 -4 4*S^ 

Vol. LXXXL S f Here 



Mere the general term is , ' ■ = - ^-j + 4-> and by writing. 
2* 2. 4, &c. for Xj we have the fum= &ۥ +. 

^ J -r^ 2.33.4 

A= - i+A. In like manner -^ + ^ + —i- + &c. = -1 + 

a- a^.34,sb.7 

hyp.Iog.2 + A-Alfo^+^+^^+&c.=li-3A + 9Bx: 

r 



If w Be negative, then , ^1 — = — ^== - ^ - ^ — &c« ^ ^-^ 

Hence -ri-. + -^ + V- + ^^-^^-A-B-C; and fo oir 
for others- of the fame kind.. 

If the general term be under this form • -^ ■ » then, i» 

like manner^, we have =!= ^ = — ^ ^+-r7. ^ ^^* 

X* .ax'^.As^m ox ^m ex «V 

[x ^, where ihc fign on the left hapd will be + or-, accordr 
ni' 

kig as r is even or odd, apd the number of terms on the. right 
is = r + r. 

Ek. IV To find the fum of ^+p^^+-^^ 

Here w=:i, »=^2, ri=2, tf= i, and the gelieral term \= 

'■WL I ' +~; now the fum of the feries whofe general 

^ ** + i ** ** 

ttermis-^is =,576674037469, by. Prop. 2.,; confequently 
the fum required = ,576674037469 - A + C = ,0 1 4063204332. 

Ex^a. If the givcA. fenes ^®\^+57IB+I^7I^ + ^^' ^^'^ 

geaeral 



«J Infinite Series, 307 

general term will be —2==--^ + ;^; hence, by 

writuig 2, 3, 4, &c. for *, we have the fum = - ,576674037469 
+ A = ,06826002938. ' 

If m be negative, then" ' "^ ':y~Z'"t'^ :^' " ^^* 



* ■ . a* 



r 

m 



Ex. 1. Tofindthefumof _-I^^ + _^ + ^-^^ +&c. 



*-ix**xx+i **x*'— 1 **-» ** * 



Here the general term is 

now, by writing 2, 3, 4, &c. for «, the fum of the feries 

whofe general term is -^ is= ?, by Prop. 2.; hence the fum 

required « ? — A. 

Ex. 2. Let the given fcries be x . a* .3 + 3 . v.5 + 5 . 6\7 ^'' 
&c. Here the general term is the fame as before, writing 2, 
4, ^, &c. for X ; and, by Prop. 2. the fum of the feries whofe 

general term is -^ is = -; hence the fum= j -A". 

Ex. 3. In like manner the fum of the fcries ^ ^^ ■ +; 
j-±_+^-i^+&c.=,22i689395io4-B. 

Ex.4- To find the fum of j-^+ 3 ^' ,o + ,^ , .^ - ^ . ^y 

'+&c. Here the general term i s-_ — — \ — =r^« — — ===* 

«■_! i-; but the fum of the feries whofe general term ia 

-^ is -i ,086662976264;, hence the fum required =. 

^08^664976264-0. 

S f a PROP. 



3oS Mr.. ViKcx M the &ums^ 



PROP., v.. 



Tofnd the Jum of the infinite feries — + JL + i. + -i_+^ jL 

IS 40 1^5 156 a59 
&c. 

In this feries the fourth differences of the denominators 
'»o; theretorc the general term muft be rcpreknted by 

ax^^bx^-cx-^d * ^^^^^ therefore 2^ 3, 4, &c. for a:, and we have 
8^ + 4^ + 2^ + ./= 15, 27^ + 9^ + 3c + ^=40, 64J+i6^ + 4r 
[+^=&5, 125^1 + 25^ + 5^ + ^=156; hence ^= i^/i= u c=u 
^" I, and the general term is -^ ? =:J I o-A^JLo. 

&c.; hence the fum » B - C + F-G +K-L + &c. = 
^1242700165. 



P H O F. YU 

^ofnJtbeJumof^+A+Ji^ + ^c. ad inf.. 

The general tcrms^^^i^-i-l + &c.; hence, hf 

writing 2, 3, 4, &c. for x, we have the fum=B-2D+3F 
L-&C. = ,1471 15771469. 

In like manner^ + ^+-ij + &c. = B+aD+3F + &c. « 

,311498999865* 



jriop; 



•J hjinttt Series, 309 



PROP. VII. 



Tof.nd ihejum of ~-^, + ^r^ + -t^. + &c. ad inf^ 

The general- term is ■^-. , '_ — a =^+;^a + 4 + &c. ? 

hence, by writiivg 2, 3, 4, &c, for a:, we have the fum = 
G+2L + 3P + &C. =,009447690684. 



FRCP. vnr. 
9V find the fum of -r — \ — .A \ — l4 ^^ — y+ &c.. 

Here the general term is =3 — - . = i- + J- ^ l &<r» 

and hence the fum = H + 3K + 6M+&c-= ^004707 14833 7. 

PROP. IX. 

Ti find the fum of the infinite feries r- — + ^ -2.+ &e;. 

o 
being a feries of the reciprocal of the figurative numbers of the 

3''^ order^ having tbefigns alternately + and — ^ 

This feries, by refolving two terms into one, become* 

7—^^ — ^ — -H r 1-&C. whofe general term*, by wri- 

'•2-33-4«S5-^-7 ^ "^ 

ting 2y 4^ 6,. &c. for x^ is ==— ^— r^-r-=4 +4+ t + &c^ 

confequently the fum = 46'^ + 4D^^ + 4F'' + &Cr = (by Cor^ 
Ex. 2. Prop. 2.) - z + 4 hyp. log. 2^ 

Coiw- 



310 Mr. ViNCE on the Sum 

Cor. Hence, as i+-L + i +I+&c. = 2, wehavei + 1 +' 

3 o lo 

JL + &c.=2 byp. I05. z, and -+^+£+ &c. «2-ahyp. 
iqg- 2. 



T n o p. 3C. 

T(7 /)!// /i^ fum of the infinite feries i — I + 1 — + &c^ 

ieing the reciprocals of the figurative numbers of the ^h order^ 
having thefigns alternately + and - . 

If we write 2, —3, 4, -51 &c. for .v, the general term 
will be -5 — = --4.---+ , +&C.; hence the fum required « 
6*+ bd^ 6/+ &c. =5 (by Prop. 3.)-- 7f + 12 hyp. log. 2, 

Cor^ Becaufe the fum of i + — 4- — + — -f &c. = — i there- 

4 to 20 % 

fore i+^+^ + &c.= -.3+6.byp.lQg.2; and-i + jL + JL +; 
&c. = 4J - 6 hyp. log. a. 



T 11 p. XI. 

To fid the fum of ^L^ + -£- + jjiL 4. &c. ad injhtimm, 

Iht general term, by writing 2, 3, 4, &c. for x, rs 
>■■. / i =-T+4 + 4 + &c.; hence thefumaA+aC + aB 
-<^&c. = ,884966993407« 

PROP. 



tf InJinUe SerUsp. 311 



PROP, xti* 

ro find tU Sum of ~i^,+_^^,+^-^,+&c. ad in^ 
finitum. 

Here the general term, by writing 2, 3, 4, &c. for x^ is 
■^ : =^-^ + ± + ^-^-ii+i^ - &c.; confc- 

;r— 1 . A* . 4P4-I X X' X iC X X X 

qucutly the fum = E-.2F4.4G-6H+9fI- 12K + &c. =? 
$01037089848 2* 

PROP. XlITv 

To find the fum ^jfiA-jB + x^- &c. ai Infinltunu 

The hyp. log. 2 = i — i- + - - i + JL-. &e. = 1+ i + I 4. 
-^^ ^ 31 3 4 5 3 5 

&c. - J-— — —^ -&c. ? hence 2 x.hyp* log^^ 2,or hyp. log/ 4, 

X iL V 

= ~ + — + — + &C.-1 - — -— - &c. Now, by divifion, 
135 as \ ' ' 

~\ = 7 - J?+:p - 87*+^*^* • ^^"^^» ^^ writing 2, 3, 4, &c. 

for Xt we have (after tranfpofition) - + - +&c. — — 

— &c. = -iA + JB — l-C-K&c. % hence, by adding equal quan-^ 

tities to each fide, we have - + - + - +&c. — il— i — i- ~: 

» 3 5 234' 

&c. = ? - f A + JB - |C 4-&C., confcquentlj \k - jB+ 4C - 
&c.= 5 -i--|-L-&c + i+ 3 +.; +&C.- |-hyp.log;4. 

P K O Fw 



J li Mr. VmcE on the Sums 



PROP. XIV. 



To find the ftwt of the infinite feries — ^+ [ 4-&Ci 

^ ^ ^ -^ ^ 2.53.74.9 

The general term, by writing 2, 3, 4, &c. for x^ is 
= -L~-L+i.^&c.; hente the fuai=iA- JB + ;G 



*.»*,+ 1 *** 4*' 8a4 

-&c= (by Prop. 13.) |-hyp. log. 4, 



To find th: f urn ejT i + i + i + 



PROP. XV. 

I 



. • . . • /o 



The hyp. log, -^ --+—, + —j+-^ + ^c. ; comfequently 

hyp. log. -^^ ^,--^--^-&c = -; hence, if we write 

a, 3, 4,&c. for *, we have hyp. log. * + hyp. log, | + &c . . . . 
^JP- log. _l--i-xi. + i + &c ~ 



3 a' 33^ *^ ^-, 

4 a' 3 * J 
- &c. &c. &c. J 

L + ! + I +&C. . . , -; but hyp. log. y + hyp. log. ^ +; 



3 4 



hyp. log.-i + &c . hyp log. ^-^= hyp. log. i x | x ± x' 

&c... .-^ = hyp.log.*; alfo^+f, + &c ^ = the 

y rum 



cf hifinite Strks. 315 

•fum of the fame feries ad infinitum^ minus the fum of all the terms 

the 'feme manner — , + ir 4- &c. . . . -\ =: B - -^— -i- - -L + * 

2^ 3^ x^ . 2n* 2«* 4n* 1 2n* 

f— J--4.&C. ; and fo on for the other feriefes ; hence, by fub- 

I2« . 

illtution, and adding unity to each fide, we have hyp. log. 

^+i.|A-|B-jG-&c.+ li + -^,+-^ + ^+J^+-^ 
. an iztr jb* iion* ' yi^ a^aw* 

[+^ + -5i-+&c.SI+i + f + J + &G. ...i; but l-fA-; 

iB-jC-&c. = ,577215664901; hence i + I + i + &c, 

.. . . .}=hyp. log. a; + ,5772I566490I + ^ + ^i-^-^,^ r^ 

Ex, I . Let xz=: 1 0000 ; then 

hyp. log, 10000=9,2 1 034037 1 95r6 
•conft. quaiit. = ,577215664961 

•^ = P00049995000 
•-^== ,000000004166 

therefore the fum required =9,787606036043 



%orfi 



3&X. 2. Let xzz 1 0000000 ; then 

hyp. log. 10000000 = 16,118095650958 
conft. quant. = ,577215664901 

-i- = ,000000049999 



2« 



therefore the fum required = 16,69531 1365858 



Vol. LXXXL T t p r o ?• 



314 Mr- ViNCE fm tht Sums 

PROP. XVI. 

^ofind the value ofax^xyxSx &c. ad infinitum^ f^PP^J^^S 
the general term to be a rational Jundlion of %. 

Let 7F be the general term, then refolve - into an infinite 

feriesy and take the fluent on both fides ; then write 2» 3, 4, 
&c. for x^ and one fide will become the hyp. log. of the given 
feries, and the value of the othec fide may be found from th^ 
tables. 

Ex. I. To find the value of ^ x ? x — x &c. ad infinitum. 

3 8 15 -^ 

t • • • 

Here the general term is -A— ; hence ^ = — -H- ^^ — ^ 

^!f^?f-&c.; henccthehyp. log.-^=iI + J-+lI^ + &c. 

Write 2, 3, 4, &c. for x^ and we have the hyp. log. i-+ hyp. log* 

I +hyp. log. i^+&e.«A+*C + |E+&c. = ,693147180574, 

which is the hyp. log. a ;. but hyp. log. - +hyp. log. i + 

hyp. log.J-+&c. = hyp. log. 1 x^ xi- X &c. confccjuently 

1 X I X i- X &c. = 2. 
3 8 IS 

Ex. 2. To find the value of - x ^ x -f x &c. ad infinitum. 
Here the g[eneral term is -r^-- ; hence - =■ - -^ =r - If ^ 

?f^|f-&c.; hencethehyp.log.^^-i + ^+i5 + &c. 

Write 2, 3, 4, &c. for x, and we have hyp. log. — +hyp. 1<^. 
i • ^ 



I 



26 



of Infinite Series, 3 r 5 

-+hyp. log. ^+&c. = B+iE-f-fH4-&c. = ,2 1 1466250444; 

or hyp. log- — ^ II ^ 5^ ^ *c. - ,21 1466250444 ; hence - x] 

?Ix^x&c.=» 1,627295, &c. 
ao 63 

Heuce wc may find the value of fuch a quantity, fuppofing 
the number of faftors to be finite. 

Ex. To find the value of - x -i x - x &c to -^ . 

135 a*— I 

Here the general term bcbg ~^, we have -j- « - ^^r-; =* ") 
J. ir-~ — ^. - &c. ; hence hyp. log. -^^=--V + 

_i l-_l; — I L- + &c.. Now write 2, 3, 4» &c. 

X . 4* 3 • 8*'^4 . »6** 

A 6 8 
for *, and we have the hyp. log. ±x — x- x &c 



_^ Si — X — -H^ -1- — -T" . • . • . — 

a»-i a g ' 3 4 *^ 



h-^-r-^T'+T-^ 



I I J. * -1- * -I. * 

J — -X 1+-5+-T+ tr 

'^3.8 a* s' 4' «* 

+ &c. &c. &c. 



But, by Prop, i 5- 7 >< I + 7+ i + • • • • ; 7* i^^PV^g- 

^^,2ii392i67549 + :^+4^+^+ I^'^;b'*'i5:^'' + ^^'' 

1 1 i T I vA * -J L-uJ 

alfo^x-+-i+ . ...^- — '^^- „ *"' 6n3^30»» 



&c.and j-§x^+^+ ... .-p-jTg »« '^ »«* " 2«3 " 4n* "T 

J &c., and fo on for the other feriefes : hence, by fubftitu- 

. T t a twn» 



31 6=- Mr, VfKCE m the Sums, &c. 

t'ron, hyp. log. -| x _ x 1 x &c ^1- = f hyp. log. a;w 

quently A x — x -^ x &c ^-^— =r the natural number 

correfponding to the right hand' fide of the equation ; hcnccj 

t X - X - X . • . . —^^5a twice that natural number^. 
13 5 2^- 1 

Ex; Let a: = I coco; then 

i hyp. log. «:=: 4,605 170 1 8598 8fi ; 

conft.,quant. =» ,120782237640 

4^484387948348 
Jl= ,000012498750 

j-j= ,000000001249 

on 



4,484400448347 the natural > number, 

correfpondiug to which hyp.- log. is 88^623^, &c., confe- 

1 2 J. 6 20000 .*' 

quently - x ^ x _ x ...... « I77,2476. 

^ "^135 19999 ^ ' 

If X be a very large number, it may be fufficiently exa£l in 
moft. cafes to take twice the natural number correiponding ta« 
the hyp. log, of i hyp. lOg^ at— ,i2078a23764p# 



i&ty^ 



f 3^7 1 



XKf. Experhnents and Oi/ervations to inve/li^ait the Qompi^jkiM^ 
of James's Powder. By George Pearfon> Af, D. F. R. S.;. 
communicated by. Sir Jofeph Banks, Bart. P. R, S. ' ' ' 

R^ad'June 23, 1791^ 

THE medicine upon which many phyficians principally' 
depend In the cure of continued fevers is James's Poiv^ 
der; but, although it has been very extenfively ufed above* 
thirty years, the public have not, I believe, been informecf 
of the particular nature of this fubftance. This powder way 
originally a patent medicine ; but it is well known that it can- 
not be prepared by following the diredions of the fpecificatioa 
in the Court of Chancery. Prefuming that I have made fome 
experiments and obfervations whioh may explain the nature* 
and manner of preparing this medicine,, and, perhaps, rtay 
extend the hiftory of antknony ; I beg leave to have the honour- 
ed preienting an account of them to the Royal Society* 

Senjtble properties of Jamss^s Powder. 

Some parcels of this preparation are white, but in general it 
has a yellowifh caft ; and this (hade is more evident in fome 
fpecimens than in others. It is faid, that this powder cannot,, 
in general, be made at different times of prccifely the fame 
ihade of yellow or degree of whitenefs* Sometimes with the 
aid of a lens a few very fmall fhining Jpicula are feen mixed! 
with powder^ Whca preffcd between the fingers it feels 

fmootb^ 



3 1 8 Dr. Pear son's Expirimentf and Obfervailons 

fmooth, with fomc rather rough particles, and it is gritty ia 
the mouth. Moft: parcels at firft are taftelefs; but in about a 
minute there is » flight brady tafte. It is perfedly inodorous. 

Specific gravity. 

This powder feels much heavier than any of the common 
earths and ftones in a pulverized ftate. One of the phials, 
nearly full, in which it is fold, reckoned to hold a quantity 
equal to twelve packets, or 480 grains, contained 470 grains 
troy weight of James's powder. This phial, filled with dif- 
tilled water to the fame height that it had been by the powder, 
was. found to contain nearly four di;jchm-meafures, or about 
240 grains, of this liquid *. 

EffeSls of fire. 

(a) The exterior part of the flame, of a candle applied, by 
means of the blow- pipe, to about one,, two, and three grains 
of James's Powder on charcoal, and alfo in the fpoou, only 
made it yellowifli while hot, but, on cooling, this colour difap-^ 
peared. The interior and hottefl: part of the blue flame turned 
this powder yellow, and when continued fo as to ignite it, a 
white inodorous fume or vapour arofe, which foon ceafed; 
and though the heat was continued, the powder neither ap- 
peared to dimini(h nor melt ; but, ou cooling, a flightly co- 

* After this Faper had^beea readU ^b experimeat) ia a di&reot maMier, was- 
mad^ to. afcertaiq tJK fppQific grayity of tbis powder. The quaoiity which nearly 
£Ued a phial weighed 437 graiqs ; aixd filliag the fame phial, to the fame height, 
with diilillcd water, the temperature of which was 65% the water weighed jt 56,2 
grains. The reafon of the variation in thefe refults, in making ufc of difiercnt 
parcels of this medicine, will be obvious, from the following, account of its 
preparation, and the great difficuUy of ; datcnB9ioiDg„ with. accuriKyi tbe fpeeiiic 
^cavity of powders* 

hering 



M the Cothpoftion of James's Po'wdtr. 319 

hering white folid, about threc-fourtKs of the origmal weight 
of the- powder, was left. If the flame was fuddenly with- 
drawn, as foon as the white fumes appeared, they afcended 
with a kind of revolving motion. 

(A) Two grains of this powder, mixed with about three of 
pulverized tartar, being expofed on charcoal to flame applied 
by the blow-pipe, the mixture turned black, boiled, and fwelkd ; 
and by continuing to apply the flame, the coaly matter of the 
tartar . difappeared, a part of the mixture ful'ed, and in that 
ftate feveral fmall, filvery, apparently metallic grains vyere 
perceived. Oa cooling, they were feen with the naked eye, 
or with a lens, adhering to an irregularly figured, partially 
melted, whitifli mafs. On a fecond application of the flame, 
thefe metallic globules difappearcd. 

{c) James's Powder, with glafs of phofplioric acid, melted 
into an opaque yellowifli globule while hot, which on cooling 
grew whitifti. 

{d) This Powder, with feveral times its weight of melted 
borax, afforded a colourlcfa tranfparent glafs while fluid; but, 
on adding a larger proportion of powder, the globule turned 
opaque, and when cold became of a milky whitcnefs. As 
the James's Powder mixed, or melted, with the fufed fait, flight 
cxplofions were feveral times heard. 

( ^ ) With foflSl alkali, in the fpoon, this powder apparently 
fufed, and afforded a colourlefs tranfparent fluid in a ftate of 
rotatory motion ; but on cooling it grew opaque, and had a 
horny appearance* 

(/) 100 grains of this powder in a two-inch Englifli cru- 
cible, the cover of which vras luted on it as clofdy as poflible, 
were expofed above two hours to a fierce fire in a melting fur- 
nace. On breaking this cruciblei when cold, the powder was 
5 found 



^ao Dr. Pearson's Expetimentj 6nd ObferDatiem 
found changed into an entire very hard white iblld^ i*eceivrtir- 
its figure from the veflel, and weighed 95 grains. On break- 
ing this hard folid, the lower part of it feemed to be vitrilficd, 
or in a ftate of enamel ; and being powdered^ it afforded a much 
whiter powder, and of greater fpecific gravity, than before. The 
degree of fire denoted by Wedgwood's pyrometer was i66^ 

Thefe experiments indicated the prefence of a. metallic calx^ 
a part at leaft of which was that of antimony, x»ixed with 
earthy matter. 

Experiments with different men/lrua applied to Jameses Powder. 

L With water. 

300 grains of this powder were digefted for fevcral hours la 
twenty- feven ounces of diftilled water, and then boiled for one 
hour. While boiling the water appeared milky; but in half a 
minute's time, after withdrawing the lamp over which it boiled^ 
the liquid became nearly clear, and the fediment depofited was 
apparently the powder undimini(hed in quantity, and in other 
refpedls unaltered. While hot the liquid was decanted upon a 
filter of feveral folds of paper previoufly weighed, through 
which twenty ounces of quite clear liquid, like water, readily 
paffed. Very little powder -could be perceived on the filter ; 
but when it was well dried, it weighed fourteen grains more 
than before the experiment. The filtered liquor was taflelefs. 
In about three quarters of an hour it grew flightly turbid; and 
in ten minutes after became milky. On flanding eight days 
longer, the milkinefs diminifhed, and a fmall quantity, per- 
haps four grains, of clofe white fediment, firmly adhering to the 
fides of the vefTel, were depofited. A little of this flightly 
ixrilky fluid being made hot, it grew quite clear, and on cooling 
^ 7 turned 



Mibjs Campofition of James's Bowder. 3^1 

^rned milky as before, or depofited a fediment; therefore, 
this milkhjefs depended on cold \yater diflblviug a fmall^ 
proportion of James's Powder than hot water. The whole of 
,j(^e. filtered xmlky liquor \vas 4>oijred upon a filter as before, 
through which it palled without any diminution of its turbid 
jappearance ; and, on drying, the filter was found to have in- 
creafed only a quarter of a grain in wejjjht. Some of the 
.vapour ^that arofe during the ebullition being condeufed was 
found to be piure water. 

On a repetition of this experiment the phenomena abovp 
related were always obfervcd ; but the femi-vitrified James's 
^Powder above-ipentioned (/) afforded a mi^ch lefs milky fluid 
.and fediment than the powder ufed in the preceding experiment. 

In order to determine the kind gf fubftances in water 
after boiling in it James's Powder, the following re-agents 
jwere added tp the above. filtered liquor. 

!• Acid of fugar fometimes occafioned immediately more 
turbidnefs, and at other times tranfparency was inftantly pro- 
duced ; but in alt cafes^ on ftanding, more fediment fell than 
from the filtered liquor alone. 

2. Muriated barytes in about an hour rendered this liquid 
evidently njore turbid, and on ftancjing more fediment was 
depofited than from the filtered liquid to which nothing had 
been added* 

3. Lime-water occafioned imniediately a curdy appearance. 

4. Infufion of turnfole was fometimes turned to a flight 
jed I but in general it was not altered in colour. 

5. Nitre of filver produced in a few hours a flight fedicnent. 

6. Pruflianated alkali of tartar occafioned no alteration im-* 
.mediately, nor for four days after adding acetous acid to this 
.mixture. 

Vol, LXXXI. U u 7. Mild 



3 22 Hf* Pearson*s "Exfertntents and Ohfervattons 

7. Mild alkali of tartar, and likewife mild foffil alkali^ 

though boiled in thi^ liquor, did iiot occafion any additioml 

precipitation. - 

The fediment that fell, on merely ftanding, from the above 

filtered liquid, was next eXamiiied. 

1. It did not difToive in 100 times its weight of boUihg hot 
concentrated acetous dcid ; nor^ 

2. Was it apparently a<fted upon by boiling with mild atkali 
of tartar; for, after decanting the clear liquid of this mixture, 
the fediment from it was not diflblved by a large quantity of 
acetous acid, but readily by marine acid^ 

3. This fediment immediately difappeared on pouring lipott 
It a much fmaller quantity of marine acid, and alfo of acid of 
nitre, than had been applied of acetous acid^ without any folur 
tion enfuing* 

4. To one portion of this folutiorr in marine acid juft 
TOfentioned, was added gradually lixivium of alkali of 
tartar ; after the efFervefcence hdd ceafed to be produced, the 
firft drop dccafioried a turbid appearance, ahd the liquM did not 
grow clear again oh adding a large proportion of Vuiegar to 
make it ibtir. 

5» Another portion of this foliation in hlarine acid, 
teing boiled tb tarry off the faperabundant acid, was 
poured into a large proportion of lime-water, by which it was 
rendered cloiidy, and did not become clear again oh adiJing 
concentrated atetons acid to liciake it four. 

6. To a third portion of this fdlutidn in marine Acicl, from 
which the rcduridaht acid had bien carried off, tWeiity dfops of 
Pruffian alkalihe lixivium were added, ^hich imniediately 
tnmed it of a bluiih caft without diftui^binfg its tfahfpafency; 
and, after ilanding four days, a fmaller quantity of j>'ale blue 

fbdiiticat 



M the Comp^fiiton nf JamE8*$ Ptmier. jf j 

fedlment was depofited than had falleu from a (Quantity of 
^idilled water equal to this muriatic folution, to which ha4 
been added twenty drops of this PrufHan alkaline lixivium* zxA 
one-fourth part of a drop of muriated antimony. The. fame 
Prudian alkali mixed with rinegao on ftandingt turned bluiih^ 
but depofited nothing. 

7. Though the fediment that fell in the filtered fluid, p. 
32p. on merely ilanding, difTolvtrd in the nitrous acid as above 
•mentioned; yet, when this acid was added in a fmalle£ 
proportion, but to render the mixture four, a partial folutioa 
only took place. On adding, however, a very fmall quantity 
of marine acid, the folution was total, and with lefs fuper* 
•abpndance of this menftruum than of the nitrous acid ia 
^bich a part remained undiflblved. This folutioa 

{a) With water depofited Algaroth powder : 

{If) With Pruffian alkali turned bluifh, and^ on {landing, a 
^mall quantity of fediment took place. 

(c) A bright plate of copper, immerfed in this folution* 
^id not appear to be at all whitened, or rendered paler. 

(^) Muriated harytes rendered this folution very turbid 
infiantly. 

{e) Acid of fugar produced no change, except in two or 
three days a very minute portion of fediment; but the faccha* 
rated foda immediately occafioned a flight precipitation. 

(/) Alkali of tartar, fully aerated, rendered this folutioa 
ilightly turbid ; but cauftic mineral alkaii induced no changp. 

[g) Lime-water, in a fmall proportion, did not affedk the 
tranfparency ; but in a larger produced copious clouds. 

The Jam£s's Powder which afforded the folution in water* 
oa which the experiments above related were made, was 
WUcd a fecond time in eighteen ounces of diftilled. water for 

U u a two 



3Z4 i^^* Pearson's Expiriments hnd Ohfervatkns 
two hours. The decanted and filtered liquid on cooling grew 
lefs turbid thaxi before, p. j20. and depofited lefs fediment. 
The filter, on drying, was found to have gained ten grains,* 
though very little powder could be feen upon it. The 
ex|)eriments above related, were made on this filtered 
liquor, and in a (lighter degree the fame appearances were 
obferved. 

The James's Powder remaining after thefe experiments, 
being Well dried, weighed 260 grains, and therefore was found 
to have loft 40 grains, partly by folution in water, but ftill 
more by its adhering to thd filters. 

. I wiflied to know the proportion in which Jam£s*s Powder 
diflblved in water ; and therefore evaporated, in a very thii^ 
light glafs pan, previoufly weighed, twenty-four ounces of' 
the filtered liquids, p. 320. and p. 324. Very little precipita* 
ted matter appeared till nearly the whole of the liquor was 
evaporated ; and, when the whole was carried off, a taftelefs' 
whitifli, leafy, or mica- like fediment, but in fome parts black, 
was left, that weighed fix grains. This fediment required* 
al>ave 100 times its weight of hot water to diflolve it. It was 
boiled in 500 tiipes its weight of diftilled water, and it palled 
through feveral folds of filtering paper rather turbid even while 
hot; nor could it be rendered clear by repeated filtration 
through paper. This filtered liquid, 

{a) With infufion of turnfole and turmeric, betrayed no 
alkaline fubftance, nofdecifively any acidity. 

{b) Lime-water rendered it curdy ; and on adding vinegar, 
it grew milky. 

if) With acid of fugar it grew clear ; but, oa ftanding, 
was more turbid than before* 

(^) Salitcd 



en the Comfofition of James's Powder. 325 

{d) SaUted barytes made it inftantly turbid. 

{e) Alkalies, mild and cauftic, induced no change. 

(/) Pfuffiau alkali produced, only a clear grccnifli colour, 
after the addition of vinegar, and long {landing. 

(g*) A very fmall quantity of marine acid rendered ir quite 
clear; but it required much more nitrous acid to produce this 
efFeft ; and this mixture did not whiten copper. 

(J)) With nitre of filver the filtered liquor turned of a 
fomewhat bluifti hue, and afterwards curdy. 

The undiflbWed matter that remained on the filter, p. 324.' 
1. 22. above mentioned, appeared, on examination, to be the fame 
kind of fubflance, with a larger proportion of iron, as that 
which was diflblved by water, the experiments on which have 
been ju/l mentioned. In particular, it afforded Algaroth 
powder, but did not whiten, in the fmatleft degree, a copper 
plate. 

The following conclufions may, perhaps, be jufliffibly; 
drawn from thefe experiments on James's Powder with' 
water. 

I. That the whole, or a part, is foluble, or at leaft may be* 
fufpended, in about 2000 times its weight of pure water cold ;- 
and in about half this quantity of boiling water. 

2* That this folution contains calcareous earth united to an 
acid, or fome other fubftance, from which it cannot be dif- 
united by cauflic OF mild fixed alkalies ; therefore, the preci- 
pitation by muriated barytes cannot be referred to vitriohted* 
lime» 

3. That this folxitibn contains^ a- metallic calx, a part of 
which at leafl is that of antimony uncombined, or at leafl not' 
united to any acid with which it forms a compound ibluble in' 
water; 

4. That 



^aJi JDr. Pearson's Expinmtnts and O^firvailwj 

4. That the fubftancc m the nitrous folution of the part of 
James*s Powder that had been diflblved in water, which pre- 
cipitates lime from lime-water, and which precipitate is not 
foluble in a large quantity of vinegar, is, probably, phofphoric 
acid from phofphorated lime decompofed by nitrous acid* 

The precipitation by muriated barytes and nitrated filvef- 
could not be from vitriolic and n^arine acids coaiiftenily with 
the preceding experiments ; «nd I could not have conjectured 
what was the ingredient in James's Powder which occafioDS it, 
if I had not found, that muriated barytes is not only a ted of 
vitriolic but of phofphoric acid united to lime and alkalies; 
and the acid of phofphorus will alfo produce a turbid appear- 
ance with nitrated filver. The calx of iron, in the above 
experiments, is in perhaps too fmall a quantity to be confidered 
in any other li^ht than as an accidental fubftancc 

II. H^uh acetvus acidl 

The 260 grains of Jameses Powder, remaining after boil* 
ing 3C0 grains of it in diflilled water, and after the una- 
voidable wafte of it in the above experiments with water, 
were put into a tubulated retort that would contain four ounce- 
meafures, on which were poured three ounces of concentrated 
acetous acid, the fpecific gravity of which was as 106 to 100^ 
the neck of the retort being immerfed in quickfUvi^r, and the 
tubulated part being immediately clofely flopped No e&r- 
vefcence was perceived ; nor did any elaftic fluid rife during 
twenty- four hours into an inverted veflcl of quickfilver ; and 
when heat was applied to boil the acid, nothing hut the com* 
mon air of th^ retort and a little water and acetous acid came 
over. 

7 This 



en the Coinfojitm of Jameses Powder.. 527 

• Th^is mixture of dcetous 'acid and powder being poured, 
^ile hot, on a filter of two folds of paper, a clear and co- 
loUrlefs liquid pafled through, that remained fo, when coldi 
Without any fediment. The filter, with the powder upon it, 
being Well dried, welgfted ten grains more than the fum of 
their weight feparatcljr before the experiment ; but the powder 
being carefolly fcraped off weighed only a little rriore than 240, 
grains, and appeared ko have fuffercd no change in ita pror 
perties. 

Tliis filtered liquor was fubjefted to diftillatbn ; it remained 
clear till about half of it had conle over : but then k became 
rather turbid, and grew more fo to the end of the diftlllation. 
There remained in the retort ^apparently fonr or five grains of 
broWn fediment, thst adhered ^ery clofely to the bottom and 
fides of It, nearly half as high as the liquid reached. 

ift. This acetous acid, in which JaMes^s Powder had 
been boiled, and afterWai'ds diftiHed, was found to contain 
no earth, ftlt, 6r toetainc matter : nor did the acid itfelf 
appear to be altered in Its chemical qualities* 

2dly, The refiduum in the retort had no tafte. It did not 
appear to diflblve by trituration in one ounce of didilled water, 
nor in lixivium of alkali of tartar, mild or cauftic. After 
toiling this refiduum In one and a half ounce of water, part 
of it feemed to be difl!blved ; and this folution being filtered 
ivas eiarained with the following re-agents. 

{a) Acid of fugar rendered it turbid, and tranfparency did 
not erifue on adding a further quantity of this acid. 

(t>) Miiriated barytes produced a confiderable turbidnef^, 
which was not removed by adding concentrated acetous acid. 

(r) Nitrated filver induced a flight turbid appearance, 

(d) Mild alkalies induced no vifible change. 

{e) Pruffianatcd 



328 Dr. Pearsoj^^s Experiments and Oi/ervations 

{e) Pfuffiauated foffil alkali occafioped a very flight opal 
coloured appearance, and after (landing fix days a very fmall 
quantity of whitifli fcdiment was thrown down, which dif- 
folved on concentrated acetous acid being added, and the liquid 
turned greenifli ; but, after fbnding, a little greenifli fediment 
was depofited, not, however, apparently more than was produced 
by a mixture of this Pruffian alkali, acetogs acid, and water. 

(/) Phofphorated foflil alkali produced no turbidnefs or 
precipitation on (landing a week ; but on the addition of •^~ 
gr. of nitrated mercury (which had been made by fully 
faturating the nitrous acid with mercury) the mixture grew 
inilantly thick, and depofited a copious white fediment. 

3dly, The remainder of the refiduum, in the retort 
jbove mentioned to have been left after diftilling to dry- 
nefs acetous acid in which James's Powder had been boiled^ 
^d not totally 'diflblve id a large proportion of nitrous acid 
diluted ; but was wholly taken up on adding a little mariqe 
acid. A great part of the fuperabundant acid of this folutioa 
being carried off by evappration, it w^s examined with the 
following fubftance.s. 

{a) Adding a little of it to a large proportion of \vater^ 
milkinefs enfued. 

(J>) The lame appearance took place with a large proportion 
of lime-wate.r. 

(c) A turbid bluifli colour was produced on adding Pruffian 
mineral alkali, and on (landing a bluifh fediment took place. 

(J) A poliQied copper plate w^s not at all whitened by im* 
merfion in this folution ; but, on adding to it .^.^ of a grain 
of nitre of mercury, the copper was rendered paler coloured. 

The deficiency of twenty grains of powder in tbefe 
experiments with acetous acid muft be afcribed partly to the 
* 2 foliitioi^ 



m the CmpofitiM of Jameses Pnwder. 3 4^ 

Ibhition in this mcnftruumj and ftill more to the wafte in 
the paper filter, and to its adhering to the retort when firft 
boiled. 

Tbcfe experiments indicated the fame kind of fubftances as 
the experiments with water, namely, calcareous earth in a com* 
binedftatej phofphoric acid ; caixofantimony andof iron. It ap- 
pears alfo, that Jambs's Powder is either wholly or partially iblu«> 
Ue in about joo times its weight of concentrated acetous ^cid,. 



IIL P^ei mtrd»s add. 

The i/^o grains of powder remaining after the experlmetlts 
with acetous acid^ pi. 327. were digefled ib the cold twelve 
hoUrs, m three ounce measures ai^ a half of purified and con- 
centrated nitrous ficid^ diluted with four ounces of pure water^ 
«nd rfacn dtftilled with a gentle beat till there remained about 
two ounce meafures. After (landing twenty*four hours, about 
onet)unce and a half of dear liquid, which was very corrofiver 
and acid, was drawn off by means of a fyphon. ^The turbid 
liquid and clofe white fedimeiit remaining, being mixed with 
one ounce of di(liiled water, were poured upon a filter of pa« 
per, and hot diftilled water was repeatedly poured upon this 
filter till it palled through almoft taftelefs. The firft portions 
of the filtered liquid, in quantity ten ounces, being mixed toge- 
ther, were fet to evaporate in a glafs pan. As foon as the 
liquor grew hot, the turbidnefs difappeared i and as the evapo- 
ratbn went on, firft clouds, and afterwards portions of fedi- 
ment, appeared in axlear liquid. The evaporation being con<^ 
tinned nearly to drynefs, a white, porous, or cellular cake 
was left, that weighed I2p grains. The liquid obtainecl 

y OLw LXXXI. X X by 



^^o Dr. Pe^arson*s Experiments and Obfervatiom 

by diftillation from the folution which left this mafs was found 

to be merely diluted nitrous acid. • 

The refiduum left on the filter which had refifted folution in 
nitrous acid, being well dried^ weighed a little more than 142 
grains. This refiduum was digefted, and boiled as before in 
nitrous acid ; and this menflruum^ diflilled from the refidaum^ 
being evaporated to drynefs, afforded 6,5 grains of a whitiih 
mafs. The refiduum left on the filter after this fecond application 
of nitrous acid, being well dried, weighed 132 grains. 

The mafs of 1 29 grains, left on evaporation of the above folution 
of James's Powder in nitrous acid, in a few hours began to deli* 
quefce, efpecially at the edges. Some of the deliquefcing part 
of the mafs was difTolved in one ounce and a half of water^ 
forming an opal-coloured folution, with a white fediment. 
This opal-coloured folution being filtered was examined. 

(a) It rendered lime-water milky ; and the milkinefs did not 
difappear on adding concentrated acetous acid, but readily on 
pouring into the mixture a tittle acid of nitre. 

{b) It turned thick and white, and foon depofited a copious 
fediment of white matter, with a few drops of nitrous fblu* 
tion of mercury ; and became turbid alfo with nitrated filver. 

(c) With muriated barytes it became very turbid, and re* 
mained fo after adding acetous acid; but grew clear again. on 
adding nitrous acid. 

(^) Acid of fugar produced a turbid appearance. 

(J) Cauftic volatile alkali produced very little precipitation j 
but a copious one took place with mild alkali of tartar ; which 
precipitated matter, after decanting the clear folution^ was 
nearly all difTolvcd by acetous acid, and the remainder was 
readily taken. up by the marine as well as by the nitrous 
acid. 

(/) PrufSaa 



• en the Compofition of James*s Powder. 33 r 

(/) Pruflian alkali occafioned a light blue colour, but no 
turbid appearance till the mixture had flood feveral days, which 
was then flight, 

(5^) No change of colour was produced on a copper plate* , 
A little of the foft and deliquefcing part, juft mentioned to 
have taken place at the edges of the folid mafs^ tailed bitter 
and four. It melted under the blow-pipe into a horny kind 
of globule ; but the dry part of this mafs could not be fufed 
by this means. 

This ounce and a half of folution being confumed in thefe 
trials, the fame quantity of boiling diflilled water was poured 
on the precipitate or part not diflblved by this quantity of 
water on the firft afFufion. After {landing and boiling, the 
precipitate appeared to be but little diminiflied. The clea^r 
liquid did not as before render lime-water turbid ; but a preci- 
pitate enfued with nitrated mercury, which on comparifoa 
was found to be a more delicate teft of phofphoric acid than 
lime-water^ This folution alio, by this fecond aiFuiion of 
water, did not as before grow thick with mild alkali of tartar, 
nor blue with Pruffian alkali* The fediment, undiiTolved by 
thefe two applications of water, did not totally dilTolve in a 
fuperabuudant quantity of nitrous acid ; but completely and 
immediately in a fmaller quantity of marine acid; and this 
iblution in marine acid, witbajarge proportion of water, pro- 
duced milkinefs ; with Pruifian alkali, it turned of a deep blue 
colour; it did not whiten copper; faccharine acid and falited 
barytes only flightly diilurbed its tranfparency. 

By thefe experiments I found the folution of James's 
Powder in nitrous acid contained, probably, a pretty conii- 
derable proportion of calcareous earth united to both nitroi|s 

X X 2 and 



'532 Br. Pbarsok^s Experiments' and O^Jerva^onr 

and phofphoric acid ; a little phofpheric acid in a fcse fttfe ; 

and a fniall propartion of calx of antimony and of iron. 

Ninety grains of the dry part of the above mafe (^ \z^ 
grains, p. 329. were repeatedly triturated and (figefted in alco- 
hol till almoft nothing was taken up by it* This fblution, 
being filtered^ was evaporated to drynefs, a«d aiierded zo 
grains and a half of a fine white fait, very bitter, which,, oa 
expofure to the air, foon becaine liquid, but very turbidi. 

The powder that had thus ceafed to yield any thing further 
to alcohol was repeatedly triturated and boiled in pure water,, 
till the liquid palled taftelefs through tl>e filter ; and the filtered 
liquors, being evaporated, left eight grains niore of a lefe bitter 
and lefs deliquefcent fubftance th<in that frona alcohoL Part 
only of thefe eight grains was {bluble readily in water; zvA 
they appeared to be a mixture of the faline matter difiblved m 
alcohol, and of the infoluble refiduum in that meiiftruum. 

The powder remaining on the filter after thefe foliadons ii» 
alcohol and water being dried^ weighed nearly 59 grains* It 
was white and taftelefs, 

I next examined tfeefe produfts more particularly 4^ and frfi 
the twenty grains and a half which had beea diffblved xm 
alcohol. 

{a) With a large proportion of water it produced a rather 
turbid appearance, and^ after {landing, aiediment of cakaroots 
earth was depofited. 

(*)Thislaft folution (O^^^^S filtered, with mUfl aUealies^ 
grew very thick, and depofited a fedknent that was readily 
taken wp by acetous acid. 

(c) With cauftic volatile alkali its transparency was icaroeljr 
difturbed. 

{d) With acid of fugar it became thick and white ;. and 

White 



jon the Ctimpofitlon of Jameses Pii%»ikr. ^33 

(e) White 3*5 cream of milk with phofphorated mineral 
alkali ; the fediment from which mixture did not diflblve in 
a quantity of boiUug water that would have diflblved vitriolated 
liaie, nor in vinegar, but was readily taken up by nitrous acid. 

{/) The tranlparency of nitrated and muriated barytes was 
fcarcely difturbed. 

(g) It turned infufion of turnfole red^ 

(b) A little of the deliquefccnt fait above mentioned, that 
had been diflblved in alcohol, being made nearly dry, on 
adding to it a mixture of alcohol and acid of vitriol, vapours 
of nitrous ether were detached with ebullition 

(i) With lime-water it produced a flight lediment. 

(Jt) With Pruflian alkali at firft a pale green colour, and 
afterwards a blue colour was .produced ; but without any preci- 
pitation on (landing. 

(/) This fubftance, which had been diflblved in alcohol^ 
vras infuiible under the blow-pipe i and after being heated red- 
hot on charcoal it was no longer foluble in water. Being fur- 
ther examined, it was fi>und to be merely calcareous earth. 

This foluble part then in alcohol appeared to be nothing but 
nitrated lin>e, with fome traces of calcined iron. 

Sicondfyj The 59 grains of powder, not foluble in alcohol, 
were examined. 

{a) A mixture x)f vitriolic acid and alcohol detached frona 
this powder no nitrous ^ther, nor any vapour that formed 
^white clouds with vdatile alkali. 

(J>) It did not efFerveice, and required above zoo times it» 
weight of concentrated acetous acid to diflblve it. 

(r) Under the hlow^pipe k emitted no fmell or fume, and 
with ;great difficulty melted imperfe£Uyi affording an irregular 
^%ttredy hora-like^ opaque maik 



334 -Dr. Pearson's Experimenis and Ohfervatlom 

(d) It was not diminlffied or altered in its properties by 
boiling in lixivium of alkali of tartar* 

(^) Nitrous acid formed with it, without cfFervefcence, a 
very flightly turbid folution ; which folution produced the fame 
appearances as thofe related, p. 330, 331. 

(/) 5^ grains of this powder were diffolved in nitrous acid, 
and a great part of the redundant acid being carried ofF by 
evaporation, to one half of this folution was added lime- 
water till it ceafed to produce any milkinefs, and the mixture 
tafted of lime-water. After ftanding excluded from the air, 
the fedimcnt depofited from a clear liquid was coUedted, and 
being dried it weighed 26,3 grains. This precipitate had the 
properties of phofphorated lime, with that proportion of lime 
and phofphoric acid which forms a compound fcarcely fufible. 
The liquid in which this precipitate fell feemcd to contain a 
little phofphorated lime, but principally calcareous earth. 

(^) To the other half of this folution in nitrous acid 
(/) ^^^ added vitriolic acid, drop by drop, till it no longer 
difturbed its tranfparency. After ftanding, the clear 
liquid was decanted from the precipitated matter which had 
taken place, and the precipitate with a fmall quantity of 
water was thrown upon a filter. The filtered and decanted 
liquids mixed together were boiled till the fmell of nitrous 
acid ceafed, and there remained about half an ounce of 
acid liquor, which being filtered to feparate the vitriolated 
lime precipitated during evaporation, foffil alkali was added 
to perfeflly faturate it. During this union there was an efier- 
vefcence and a feparation of more vitriolated lime, which being 
removed, the faturated liquor, by cryftallization, afibrded 
nearly 26 grains of cryftals of phofphorated foffil alkali^ be- 

"fides 



en the Comp^tion of James's Powder. 335 

fides a little cubic nitre, vltriolated foilil alkali and iron, 
ivith fome vefliges of calx of antimony, and phofphorated 
lixne. 

The precipitate thrown down on adding vitriolic acid, and 
left upon the filter, .weighed when dried j;6,i grains, and was 
Titiiolated lime, with a minute portion of calcined antimony 
and iron. 

'^bc 69S gf^^QS, p. .350. left on evaporation to drynefs of the 
iecond folution in nitrous acid, confided of nearly three grains 
of calcined antimony, and the reft phofphorated lime, with a 
little iron. . 

. I. It appears from the above experiments with nitrous acid, 
that this menftruum, by two afTufions, in a large proportion, 
aided by trituration, digeftion, and heat, diflblved 4^4. of 
James's Powder that had been expofed to the adion of water 
and acetous acid ; but from the fmallnefs of the quantity con- 
tained in the nitrous acid the fecond time it was applied, and 
from its being piincipally calcined antimony, not more than 
two of the fix grains afforded by this folution, perhaps, fhould 
be confidered to be dijjolved^ for the reft may be fuppofed to be 
vatxtXy fufpended. 

The firft folution alfo in this menftruum was not filtered^ 
and the acid was confiderably redundant, and there was found 
in it feveral grains of calcined antimony. The real quantity 
dijfolved might therefore probably be eight grains lefs than 
the above 108 ftated. According to this mode of cialculation, 
the proportion of the foluble part of Jameses Powder in 
nitrous acid is 4-^, or about ^W- 

2. The whole of this foluble part, except a little calx of 
antimony, is, decilively, phofphoric acid and calcareous earth : 

whlcU 



55^ D^- PkAHSoN*8 I^rlimniiMiX^femaAni 
i^iich twofubft&nces m^ raa^narbiy^be fuppofedyfisomthflier 
experiments,, to have been united* tagetherv and. tor bafVei beea 
in the ilate of phofphorated lime in this powder. Coixfo* 
quently, the proportion of this^ phofphorated litney confidered 
as the foluble part of JaM£&*& powder in tfaofc experimeBta 
with nitrous acidj appears to-be ^xD/tei? Witr^malcii^ a dedo^Konr 
of I per cent, for the antimonial calx contained^ m\ tba 
nitrous acid in the above experiomits. It i& however: adceady 
obvious to fufped)*! thut the powder which cefi Aed folutaim inc 
thk menftruuni may Gootain nmre phofphoratcad lime;, and 
this confideration prevents me aligning at prefent the. above 4a 
per cent, as the whole qiKintity c£ it ia J/lmbs^s Pavvdfir.v It 
cannot however, I thinks be a fmaller proportion* 

I do not' reckon the> calx* of. iroa in thcfe cafculations, hz¥ 
caufe it is in too fmall a quantity, and is aj^iareatly only to 
to be looked upon as an accidental extraneous fufafbrnoe*. I 
fuppofe too^ that the water and acetous acid applied to tho 
Jameses Powder ufed in tbefe experiments^ carried oflFa.propt»« 
tion of its ingredients equal to that in the remaioiog powden 



I V« tFiib aanne acid^ 

The 132 grains of heavy , white, taftelefs powder, the 
refiduum after boiling 240 grains of Jam£s*s Powder 
in nitrous acid, till it had dilTolved that part for which 
it has any confiderable affinity, p. 330. were digefted for 
twenty-four hours iu eight ounce-meafures of marine acid, 
the fpecific gravity of which was 1,170, and diluted with half 
its bulk of diftilled water. This mixture was diililled in a 
7 gentle 



on tbi CompoJitiM rf Jameses Powder. 337 

gentle heat till there remained about two ounce •meafures of a 
very turbid liquor. After {landing in a jar two daySi^ it depo- 
iited a clofe white fediment, obvioufly much lefs in bulk than 
the powder added to this menfl:ruum ; and nearly one ounce 
mcafure and three quarters of clear yellow liquid were drawn 
ofF, by means of a tiphon, which was marked N^ i. 

The diftilled liquid, which was merely diluted marine acid, 
was poured back on the fediment and remaining liquid ; and 
after digeftion twenty*four hours, this mixture was diftilled as 
before, till there remained about one and a half ounce-mea- 
fure; but after {landing in ajar feveral days, the quantity of 
fediment depofited was apparently as great as before the fecond 
application of this menftruum. The clear liquor was drawn 
off* as before, and marked N'^ 2. The diftilled liquor being 
found to be merely diluted marine acid, was poured on the 
remaining liquid and fediment a third time; and, after di- 
ge{lion, the di{lillation was repeated as before. The remain- 
ing liquid having {lood upon the fediment Tome time, one 
ounce-meafure of clear liquor was drawn off, and marked N* 
3. The fediment did not appear diminifhed by this third dif* 
tillation ; but, as the decanted liquid, N"* 3. was found to 
contain a fmall quantity of fome fub{lance diffolved or fuf- 
pended in it, the marine acid didilled in this experiment was 
poured a fourth time on this reiiduum, and after dige{lion 
boiled. Having {lood feveral days, the clear liquor was de« 
cantedi and marked N'' 4. To the refiduum, after thefe four 
affufious of marine acid, one ounce of boiling diftilled water 
was added, and this mixture was poured on a filter. The pow- 
der upon the filter being well dried, was found to weigh 60, i 
grains. 

Vol. LXXXI. Y y In 



33^ -Dr. Pkarson^s Experimenis and Obfervations 

In the ounce of boiliing water that had been filtered from 

thb refiduum, I could find nothing but feme minute particles 

of that fubftance and veftiges of iron. Two or three drops of 

the liquor, N"^ i. added to three ounces of diftilled water, pro* 

duced a pretty confiderable milkinefs; and, on {landing, a 

clofe white fedimcnt was depofited. Two or three drops of 

the liquor, N° 2. produced lefs milkinefs and fediment in the 

quantity of water juft mentioned than N° i. N° 3. fcarcely 

diminiftied the tranfparency of diftilled water ; and N° 4. did 

not affedl it all. The liquids, N® 3. and 4. were diftilled till 

there remained about two drachm- mcafu res of clear brown 

liquid, with a cloudy iediment. N^3. being poured into two 

ounces of diftilled water fcarcely made it milky; and N"* 

4* did not diminifti the tranfparency of water at alL On 

evaporating to drynefs thefe mixtures of the liquors, N"" 3. 

and 4. with diftilled water ; that with N'. 3. left a yellowifli 

dry fediment which weighed 3,1 grains ; and that of N** 4« left 

2,2 grains of fediment. Nothing but calx of antimony could 

be difcovered in thefe fediments. They were reducible readily 

with tartar ; fcarcely fufible in the fpoon ; but with phofphoric 

acid eafily melted into an opaque yellowifli globule* 

The liquor, marked N"" i., being poured into twenty- four 
ounces of diftilled wat.er produced a very milky appearance ; 
and the fame appearance, but in a much lefs degree, enfocd 
on pouring the liquor N* 2. into this quantity of pure water. 
After ftanding feveral days, a white fediment being depofited 
from a clear watery fluid, the clear liquid was drawn off by 
means of a fiphon^ and the fediments being dried, that of 
N° I. weighed 51 grains ; that of N"" j. weighed 6,15 grains; 
. and both were found to be purely Algaroth powder. The wa- 
ter, viz. 4S 'ounces, in which thefe precipitates fell, being 

evaporated 



On the Cowpofitton of Jameses Powdef. ^^^ 

evaporated to dryncfs, left a little more than four grains of an 
infufible kind of fediment, which was calx of antimony, like 
that of N^ 3. and 4. with a minute portion of Algaroth powder 
and iron. 

The 60,1 grains, p. 337. which refitted folution in marint 
acid, were a lighter powder than James*s Powder itfelf, 
rather gritty, quite taftelefs. This powder was digefted in 
one-ounce meafure of concentrated nitrous acid mixed 
with two of acid of fait for a week ; and then this mixture 
was diluted with four ounces of diftilled water, and gently 
boiled till it was reduced to about two ounce-meafures. On 
cooling and ftanding feveral days, a fediment of the fame 
kind apparently, and in the fame quantity as before evapo^ 
ration. Was depofited, and, after ftanding, a clear yellow liquid 
was drawn off. The fediment, well dried. Weighed $^ grains* 
The decanted liquor being reduced by evaporation from one 
and a half ounce to about two drachm-meafures, a fediment^ 
while hot, appeared, which was calx of antimony, witli a 
minute portion of earthy matter that had (bme properties of 
phofphorated lime and calx of iron. A little of the clear 
liquor on this fediment being dropped into water produced no 
milkinefs, nor fediment, after (landing ; but the whole of this 
clear liquor, with fediment, being evaporated to drynefs, af- 
forded four grains of the fame kind of infufible calx of anti- 
mony, mentioned to have been obtained from the acid liquors, 
N"* 3. and 4* above mentioned. 

It appears then, that by repeatedly digefling and boiling in 
marine acid, and in aqua regia^ that part of James's Powder 
which -refifted 'folution in nitrous acid, which was ^{.4, p. ^SS* 
77 grains were carried off by thefe menftrua; but confidering 
the fmall proportion contained in thefe ^cids after the two fitft 

Y y 2 afiufioDS^ 



^o D^* Pea RSo^ 'a Experiments and Ohfervations 

affufions, which afforded 57115 grains^ p. 338., and fuppofing 
the calx to be neither increafed nor diminifhed in weight by 
the acids, the real quantity of foluble and fufible cal^ of anti- 
mony may be ftated to be that of Algaroth powder ; for 
the other, kind of antimonial calx obtained by fubfeqnent affu- 
{\ov\s was probably ou\y fujpended. Confequently 240 grains 
of James's Powder afforded, by the above experiments with 
marine acid, 57*15 grains of Algaroth powder, and 19,85 
grains of a lefs foluble and more difficultly fiiiible calx of anti- 
mony, with a fmall proportion of phofphorated lime. The 
refiduum, amounting to 55 grains, was of courfc next exa- 
mined. 

Experiments upon the part of James's Powder which was 
injoluble in the above menjirua. 

{a) A few grains of this in foluble fubftance could neither 
be melted nor carried off in vapour by means of the flame of a 
candle applied to it upon charcoal, and alfo in the fpoon, with 
the blow pipe; but, 

(Ji) Mixed with an equal weight of tartar, it melted on 
charcoal; and, while in fuiion, fmall, apparently, metallic 
grains were diflindlly perceived ; and on cooling they could be 
feen, even without a lens, adhering to an irregularly figured, 
opaque, whitifh mafs. Sometimes flight exploflons were 
heard while the flame was applied. The metallic grains ap- 
peared more diftinftly when this powder was mixed with one- 
third of its weight of powdered calcined bone, than ia James's 
Powder. 

(r) Ten grains of this powder were melted as above men- 
tioned, by repeatedly applying flame with the blow-pipe to 

two 



vn the Compofitkn of Jameses Pvwder. 341 

two or three grains of it at a time mixed with tartar. The 
opaque whitifli maflcs, with metallic grains in them, thus oh- 
tainedy being pulverized, were digefted and gently boiled in 
diluted nitrous acid. The filtered folution afforded nitre, and 
nitrous, acid in a free ftate, the greateft part of which fuper- 
abundant acid being carried off, the lixivium did not whiten 
copper, or throw down any calx but iron with Pruffian alkali. 
The reliduum that refifted folution in nitrous acid was digefted . 
jand gently boiled in aqua regia. On ftanding it was decanted, 
and this decanted liquid being heated, to carry off fuper- 
abundant acid and water, it affotded on mixture with water 
1,2 grain of Algaroth powder, and no metallic matter 
could be dftefted in the water excepting a little iron. A fmall 
part only being diflblved by the aqua regia^ the reliduum was 
cxpofed to the flame of a candle with tartar as before ; and, 
by the aid of a lens/ I could juft perceive two or three metallic 
grains in the fufed mals. To this mafs the aqua regia was 
again applied, and 0,75 grain of Algaroth powder was ob- 
tained, and no other mc^tallic calx was found but iron. A 
third afFufion of aqua regia indicated an exceedingly minute 
portion of Algaroth powder ; but I could afterwards per* 
ceive no more metallic grains in the rc^fiduum expofcd to 
flame with tartar, nor obtain more Algaroth powder from the 
folution of the fufed mals in aqua re^ia. The rtfiduum that 
refifted folution melted readily with a little phoiphoric acid - 
into an opaque, fomewhat yellowiih, white globule, not un- 
like calcined bone fufed with phoiphoric acid, and a minute 
portion of flowers of antimony. The quantity, however, of , 
this refiduum was fb Imall, that I dcfpaued of determining its 
nature further by more experiments. 

I Having 



34^ -Dr. Pe ARSON^s Experiments and Obfervaitom 

Having found that this infoluble powder would not melt 
with fulphur when heated'* red-hot^ I made the following 
experiment. 

{d) Twenty grains of it being mixed with three 
times its weight of fulphur, were put into one of Mr. 
Wedgwood's crucibles that would contain one ounce-mca- 
fure, which, with a cover well luted on, was put into a three- 
inch Englifh crucible, and calcined bone in powder filled the 
fpace between the two crucibles. After expofing this charge 
to a red heat half an hour, and in a white heat ten minutes, 
the crucibles were cooled ; and being opened, the pyrometer 
piece of Wedgwood in the bone aflies was found to indicate 
65*"^ and the mixture in the inner crucible had apparently beea 
meltdd into a refin-like mafs that adhered firmly to the fides of 
the veffel. Twenty-eight grains were fcraped off, which, after 
digeftion and boiling in marine acid, afforded fix grains of 
Algaroth powder. A great deal of hepatic air was difchargcd 
during this folution, and very little fulphur was left on the 
filter with the part not diflblved by the marine acid. This 
undiflblved part, which weighed fix grains, was blacki(h, tafte- 
lefs, not heavy. It was infufible with the blow-pipe, both 
alone, and mixed with fulphur and tartar ; but with phofphoric 
acid it melted into a blackifh fcoria*llke mafs. I could only 
conje£ture, that this lafi: part was antimonial calx, fo far vitri- 
fied with phofphorated lime as to be neither foluble nor redu- 
cible or fufible, except with phofphoric acid. 

(J) By a fimilar experiment, but with alkali of tartar 
twenty grains, fulphur thirty grains, and ten grains of this 
infoluble part of James's Powder, a fufed mafs was obtained 
that partially difiblved in water, and afforded kermes mineral 
odt pouring an acid into this folution ; but a great part was 

infoluble 



on the Comp^lion tuf James's Pov^der. 345 

infoluble in water and acids, and feemed to be of the fame 
nature as the fix grains of refiduum juft mentioned (// ). 
. I could only conclude from thefe experiments on this info* 
luble matter, that it contained calx of antimony ; but as to the 
proportion of it, and the other fubftance with which it is 
joined,* T conjefture that it may be about half the quantity of 
the infoluble powder; and that the other half is antimoniaj 
calx and phofphorated lime, fo highly calcuied and vitrified 
together as to refift folution in acid menftrua, dccompofition by 
charcoal, and fufion with fixed alkalies, but not by phofphoric 
acid. 

I (hould not have been fatisfied with here terminating this 
analyfis without enquiring further into the nature of this info- 
luble matter ; but 1 difcontinued this analytic inveftigation ia 
order to derive light from the lynthetic experiments which 
will be related hereafter. 

Thefe laft experiments feem to fliew^ that the proportion of 
antlmonial calx is not fo great as might have been affigned from 
the experiments with nitrous acid, marine acid, and aqua regia. 

The fubftances and proportions of them, obtained from 240 
grains of James's Powder, by the above experiments, are as 
follow : 

Grains, 

Phofphorated lime, with a little antimonial calx, 100, 

Algaroth powder, . . . . . 51 ^^ 5 

Infoluble antimonial calx, with a little phofphorated 

lime, •••••• ^9^^5 

The fame infoluble calx, with, probably, a little phof- 
phorated lime, • • • • • • 55, 

Wafte, • • ! • V ^. 

240,0 

5 As 



344 ^^« Pea!180N*s Exptriments and Ohfervations 

As it may be obje£ted« that conclunons drawn concerning 
the nature of calces might be erroneous if nitrous acid had 
been applied previoufly to fubftances containifig them, I made 
the following experiment. 



Experiment with marine acid applied to James's Powder^ which 
had not been expofed to the adiion of nitrous acid^ or any other 
menjlruum. 

50 grains of James*s powder were digefted, and gently 
boiled in two ounce-meafures and a half of concentrated ma- 
rine acid diluted with one ounce of diflilled water till there 
remained only about one ounce-mcafure, A great part of the 
powder appeared to be evidently diffolved. On cooling, cry- 
ftalsof muriatcd antimony were formed upon a white fediment, 
TJv clear liquid with the cryftals being decanted, the fedi- 
ment was boiled twice, as before, with marine acid ; but the 
fecond affufion of this menAruum brought off but eight grains 
of this powder, and the third only four grains. The remain- 
ing fediment, being well dried, weighed 14 grains. Now it 
has been fhewn already, that the nitrous and marine acids, fuc- 
ceffively applied, diffolved 444, or all but about 60 grains; 
and in the prefent experiment, the marine acid diflblved 44, 
which is in the proportion of 4.44, or nearly 4.^^ ; fo that, oa 
account of the trifling difFerence in thefc proportions, it may» 
perhaps, be fairly concluded, that the properties of the calx iti 
Jameses Powder are not altered by nitrous acid to affed its 
Iblubility in marine acid. And further, this infoluble powder 
in the prefent experiment was found to have the fame proper* 
ties as that in the former experiments. 

To 



en the Compojitm af James's PMfder. . 345 
To know whether Jameses Powder contsuned auy fubftance 
that could be decompofed by mild fixed alkaltes» the following 
experiments were made. 

Thefe experiments with fixed alkali feemed to be efpecially 
neceflaryy becauie phofphoric acid, lime, and antimonial calx, 
are ingredients in James's Powder; and it was obvious to 
iufpeiSty that this acid might be united with calx of antimony 
as well as with lime ; which phofphorated antimony would be 
decompoied by alkalies, and yield phofphorated alkali* 

ExperimenU with fixed alkalies. 

100 grains of James's Powder were boiled in fix ounces of 
ivater, with 50 grains of mild alkali of tartar, for three hours, 
and then the remaining liquid was filtered, and evaporated to 
drynefs; but the mattpr left after evaporation was nothing but 
the alkali ufed in the experiment^ with a little of the powder 
itfelf. 

The refult was the fame on making the experiment with 
cryftallized mineral. alkali inftead of alkali of tartar* 



Synthetic Experiments. 



ALTHOUGH the inability to prepare James's Powder 
would not prove the above conclufious, with refpefl: to its com- 
pofition, to be erroneous ; the being able to compofe a (ubftance 

Vol. LXXXI. Z z poffeffing 



346 Dr. Paarson^s ExperintiHts and OBftrvations 

poflefling all the fame propertiet as Jameses Powder, bj 
uniting or mixing together the fubftances (hewn by the above 
analyfis to enter into its compofition^ would afibrd all the 
proof and demonftraiion which can be had in the fcience of 
chemiftry. 

The above analyfis (hewed no eilential ingredients of 
JaM£S*s Ppwder but antimontal calces, pbofphoric acid, and 
calcareous earth, which two laft fubftances appeared to be 
united together ; but it would haire been vain and unneceflary 
labour to have attempted to make this powder by mixtures of 
any of the commonly known calces of antimony and phof- 
phorated lime ; becaufe none of them, from their well known 
qualities, could form a powder of the fame coloinr and fpecific 
gravity as Jameses Powder, and like it partially foluble in 
acids. From the above experiments, however, the proba* 
bility was evident, that this fubftance might be made by cal- 
cihing together antimimy and bone-afiies; which operation 
produces a powder called Lilb's and Schawan6ero*s fever* 
.powder} a preparatioii defcribed by Scheoobr and other chemifls 
ijoyearsago^ The receipts for this pre|>ara{ion differed in the 
proportion of the antimony to the bone a(hes, au<^ it> the ftate 
of the bone ; fome direding bone (havings to be previoufljr 
boiled in water ; others ordered them to be burnt to a(hes be* 
fore calcining them with antimony ; and ia other prefcriptions 
the bone (havings were dire^ed to be burnt with tlie antimony. 
According to the receipt in the pofleilion of Mn Bromfibld, 
b^ which this powder waa prepared forty <*f>ve year^ 2^0, and 
before any medicine was known by the name of Jambs s 
Powder, two pounds of hart's horn (havings muft, be^ boikd 
to diflblve all the mucilage, and then, being dried, be cal- 
cined with one pound of crude antimonyi till the ibiell of 

fitlphur 



on the Compojition t>f Jamss's Pawier. 347 

fulphur ceafes, and a light grey powder is produced. Th^ 
fame prefcription was given to Mr. Willis, above fbrty years 
ago, by Dr. John Eaton, of the College of Phyiicians,. 
with the material addition, however, of ordering the calcined 
mixture to be expofed to a great heat in a clofe veiiel to render 
it whUt. Mr. TuRNSR made this powder above thirty years 
ago by calcining together equal weights of burnt hart's horn 
and antimony in an open vefiel, till all the fulphur was driven 
off, and the mixture was of a light grey colour. He likewife 
was acquainted with the faA, that by a fufficient degree of fire 
in a clofe veflel this cineritious powder turned white ^. Mr. 
Turner alfo prepared this powder with a pound and a half of 
hart's horn (havings and a pound of antimony, as well as with 
fmaller proportions of bone. Schroder prefcribes ^qual 
weights of antimony and calcined hart's horn i and PbTsmirs 
and MicHABLis, as quoted by Frbderic HbPFMAK, merely 
order the calcination of tfaelfe two fubftances together (aifigning 
no proportion), in a reverberatory fire for feveral days. In the 
LiOndan Pharmaeopmia of 1788, this powder is called Puhis 
antimoniaUs ; and it is directed to be piepared by calcining Coge* 
th^f equal weights of hart^s horn ihavings and antimony. 

Powders made ffom various proportions of antimony and 
bone-a(bes, after iblution in nitrous acid, left a refiduum of 
antimonial calx much lefs or greater in quantity than James's 
Powder did by the fame menftruum, except two of Mr« Tur* 

* It is probably that tbit powdor ^¥U mtde fcc fevenl jfK^t% witb merely the 
heat nficeffaryr to caciy off thi& fulpbar ^od calcine the bope^ in ^n open veflel 
over a charcoal fire in a common grate, and confequently it was of a light clay or 
afii colour. In thb manueTi Mr. BaoMPiELo told me^ he prepared Schawan- 
iekg's Powder 46 or 47 yean ago. In property of tummg white in a greater 
^ree of *&i» appcan to h«r4 teen a fulifeqiient 4iifi0v«rf « 



2^^ Dr. P&iftltls<w*'$ Experiment and OBfefvaikns 

vmCs pioporttoris, . vi%^ two parts of antimony and one of 
calcined borieyjSiid joqual weights of bone (haviogs and and- 
n^oiiy. . The qoaatky of this calx was, however, greater \\\ 
the/pow/Jcr irbm the former of tbefe two laft proportions than 
the: htter of tbcrii; which latter correfponded fometimes- 
exadlyi and always nearly, with the weight of the C2tlx frota 
9fgivea weight- of Jambs's Powder. This calx afforded alfo 
the fame proportion of Algaroth powder as the calx in James's 
Powders aud the iufoluble part of the calx afforded metallic 
gralna like thoib frooar the infolubk part of the calx ia that 
powder. 

I found then an exa£l correfpondence between what I eonfi- 
der to be the ^kntial and peculiar properties of James's Powder, 
and the properties of a powder made by uniting or mixing 
together the ingredients of James's Powder found by analyfis. 
But» in order to (hew the identity or difference of the qualitie; 
0f thefe two fubftances, I made comparative obfervations oa 
: them, and repeated tlie above analytic experiments on James's 
Powder with the preparation made by calcining together equal 
weights of bone ihavings and antimony, in an open veflel) to 
carry ioff the fulphur, and then in clofe veflels applying^fueh a 
degreeof fir^as to render them white ^ thatb, oi^ the fame pre- 
{uration as-.the Puhis antimonialis of the hon^on PSarmacopaia^ 

YirStf I compared, more particularly, the feniible qualities 
of fev^ral di&rent fpecimea&of James's Powder with various 
parcels of the Pulvis antimonialis made by different chemifts^ 
All of thefe would be called white powders, but not two of 
them were fo in the fame degree. Moft of the papers of the Pul-^ 
vis antimonialis were whiter than thofb of James's Powder ; but 
others were of a very light ftoiie colour^ and fbme had a (hade 
of yellow, fo as to re&mble very exadly James's Powder; 

• . but 



on ibeCompoJitlon of James's Ponder. ' ^^9 

but all the parcels of James's Powder had either a fliade of 
yellow or of ftone colour, and none were perfeftly white, or 
io white as fbme fpecimens of the Pu/vis afaimonialis. Some 
of the parcels of James's Powder and of th6 Pu/vis anfimoni^ 
alis tafted brafly ; and other fpecimens of both powders had no 
tafte. All of thefe powders were gritty. Moft of the parcels 
of the Pulvis aniimonialis were a little fpeclfically heavier thaa 
thofe of James's Powder. The.fpecific gravity of both pow- 
ders was increafed by expofing them to.fuch ai degree of fire as 
brought them into almoft a femi*vitrified (late ; and, on the 
contrary, the fpecific gravity of the Pulvis antimonialis was 
lefs than it is in its ufual ftate, when made in fuch a degree of 
fire that the mixture preferves the powdery form. 

The experiments with water on . the Pulvis antimonialis pro- 
duced the fame kind of appearances, but more flightly than 
thofe With James's Powder ; for the hot folution of the for- 
mer grew lefs milky on cooling than that of the latter, and 
on evaporation to drynefs lefs fediment was found of the folution 
of Pulvis antimonialis than after that of James's Powder *• 

The experiments with acetous acid on the Pulvis antimoni^ 
alis (hewed, that this nuenftruum diflblved fonoetimes a greater, 
and fometimes a fmaller proportion of it than of James's pow-* 
i3er ; and the difiblved matter was found to bo autimooial calx, 
pbofphorated lime, and calx of iron, and no other fubfbnce. 

It has been already faid^ that the proportion of foluble mat- 
ter in nitrous acid was the fame, or nearly fo, of the Pulvis 
antimonialis as that of Jame!s*s Powder; and this difiblved 
matter was phoiphojic-lcidi calcareous earth, with a little antt* 
monial calx, &nd a toinute portion of calx of ifon, as exa&ly 

* The reafon for this difference is aligned ia another place.^ 



35^ ^ Jbr,l?&i^iLiOV^z Experiments and Obfervations 

^% coul4 be ^Kp^ded from the nature of the fubftances and the 

experiments, in the fame^prdportion as thofe in Jambs*s Powder^ 

The Algarotb powder, obtamed by means of folutioii of the 
Pulvis antmomaiis in marine acid, was in the fame proportion 
as nearly as could reafonably be expe£bed from the nature of 
the experiments as that obtained* frq^ Jamss^s Powder* And 
the part that redded iblution in thistmenftruum was partially 
reducible to a metallic fornix and had otherwiie the fame pro- 
perties, as far as difoovered, aa the inioluble part of James's 
Powder. 

Having now formed a powder pofl^^d of properties (imilar in 
kind to every one of thofe afcertained in James's Powder, with 
fcarcely any difference in the degree of them, if it be thought that 
among thefe projierties are thofe which are efiential and pecu- 
liar oties of James's Powder, the conclusion that thefe two 
are the fame kind of things muft be admitted to be jufl:. The 
iiaturjs of one of the ingredients of James's Powder, viz. the 
irreducible part of the insoluble matter, p. 34a. is not fully 
elucidated by the fyathetic experiments; but in fo far as they 
ihew, that this part equally extfts in the powder formed by 
cabining together antimony aod bone, which is concluded to 
be, Jambs*6 PoWider, the objedion againft the ^onclufion with 
refpe^k to the identity of the two fubftances, on the! ground of 
this inconfiderabld part of Jam^*s Powder not b^ng well 
undf r^xxxit muft be of Iktk umght; 

Several reafons, more interefting to my(elf than to the Society, 
ifiyduced me to aothaiticate by additkitial teftimoaies tbofe ana* 
lytic experimtintfti which may he coniiileped'to be mor^' decifive 
than the reft for eftablifiiang the identity oflj amss's Powder, and 
a powder formed by calcining together antimony and bone- aflies* 
Ijthere£(>re requefted Mr. Cavallo and Mr. Turner to be 

7 prefeot 



en tbi Compe/ltidft df jAMfis^i Pi>wJ^r. f^t 

prefent when I made thofe experiments on the FuMs antimoni^ 
alis^ prepared by Mr.GRiFPiN,of Apothecaries* Hall; and /ames^s 
Powder. Having, in the prefcnceof thele twoGentlemen*, broken 
the feal of a phial of Jamb»'s Powder, bought of P, New- 
BERV, and taken out of it the quantity required for the expe^^ 
riments, the bottle was i^ain fealed by Mr. Cavallo with' 
his feal, as well as the plial from which was taken the Pulvii 
antimonialis. Should any experiments be publiffied,- which 
eftabliih different conclu(ions from thofe contained in this Pa- 
per, with refpefik to the identity of thefe two powders^ I (hair 
be happy to endeavour to afcertain the truth l^exj^eriments, on 
the ]?emaining parcels of the two powders, in the prefence of 
competent judges. 

I (hall next relate the experiments m^ with the view o£ 
conBrming or invalidating the coiKluiions drawn from the 
above analyfis, with refped to the ingredients and proportk)ns 
of them in James'^s Powder; and by which I efpecially eh-* 
deavoured to n>ake fuch antimonial calces as this fubftance 
contains, by procefies different Arora tbo(e above related. 

EXP. !• {a) Hart's horn (havings, of fix dififerent paiccls, 
well dried, feparately calcined in the fame manner, and appa- 
rently to the fame degree as when calcined with antimony to* 
make Lile's Powder, afforded a light brown coar^ powder,' 
with a few thin light black pieces, and lo$ from 43 to 48 /rr ' 
ctnl, of their weight* The mean lo£f bf weight, of Gosrfe, wa^' 
45f ptr cent. 

(^) This calcined bon^ (fl), being puirerised, was expofed 

to a greater degree, of fifb,*' in clofe veflels, than that netfefflaiy 

to render the cakined mixture of antimony and bone^aflie^' 

white. The k)fs of weight by this iecond calcination or expd- 

iiire to fire was from two to three ftr tent. ; and the afiies 

-* Dr. Clarke alfo wai prcfcnt at tbc b^gioMng of ibefe ezpcriments. 

were 



35^ Dr. PsARSON 's Experiments and Obfel^vations 

were as white as fuow* The total mean lofs of weight, bjr 

thefe two calcinations^ was then tVtt- 

BXF. II. 2000 grains of coarfely powdered antimony were 
calcined in an earthen difli, as in making Lilb*s Powder, by 
conftantly raking them about for above three hours. During 
a great part of this time the veil^l vi^s.red hot at the bottom; 
and for the laft hour the fulphureous ^mes had entirely ceafed. 
The calx thus produced was of a pale bluilh colour ; it melted, 
in a iow degree of heat, into an opaque, fcoria-like brittle mafs ; 
it yielded no hepatic air with marine acid ; it weighed 1409 
grains, or the antimfuiy loft nearly 29$ per cent. The pyro- 
meter in the veflel<wi<^ th« antimony during its calcination, 
was contra£tcd to the 6th degree of Wedgwopd's fcale. 

The fum therefore of the lofs of antimony and bone by cal- 
cination in this manner, feparately, was 37! per cent. Thefe 
two fubftauces were in the next place calcined together in the 
fame manner in an open veflel, as abpve nsentipned. 

£XP. III. 2000 grains of ^utimony frpm the fame parcel as 
that in the laft experimeptsand^n «quai weight of hart*s 
horn ftuvings taken from the £|me parcel as thofe were in 
j^xp. 1* were calcined togethex in the fame manner that thefe 
fubftances had been.feparately# During the firft quarter of an 
hour, the mixture fmoked, was bl^ck, fineUed ftrongly of 
iMlpbuTf and £slt fpft. For half ajo hour more, the fnoellof 
fulpbur CQntinuedy the mixture turned b^own, ^n'd the bone 
was reduced to a(hes. At the end of this time, not only the 
bottom, of the ve&l might be kept red hot without any iigns 
e£ fttiloil ; but the fmell of fulphur, though weakly, couti* 
i|ued for half an hour more in a heat to • keep a great part of 
the mixture red hot. At this time the fulphureous fmell rather 
iuddenly difappparpd, and could pot.be perceived^ though a 

little 



on the Compqfition of Jameses Po^ir. 353 

Kttlc of the mixture was made quite red hot for a quarter of 
an hour further; during which no fume waft ieen, or fmell 
perceived. After cooling, a light grey or cmeritious heavy 
powder was left*; on examining which, argentine jl^/Wtf were 
ieen in the larger grains of this calcined fub{lance« It weighed 
22CO grains, therefore the lofs of weight was 45 per ani. 
The Wedgwood pyrometer pieces indicated 8^ In other 
fimilar experiments the lofs, by calcination, waefrom 37 to 41 
fer cent. ; therefore the mean propcMtion loft in chcfe experi- 
ments muft be ftated at 41 per cenU 

It appears, that the calcination of antimony W4th bone*aihes 
is much more fpeedy than when by itfelf, but the degree of 
fire was a little greater in the laft estperiment than in -that with 
antimony alone. Coniidering the nature of theie experiments^ 
perhaps, it may be more reafonable to impute the 3! percent. 
greater lofs in this laft experiment than the fum of the lofs in 
Exp. I. and a. to the greater infenfible fublitisation of the calx 
from more fire in one cafe than in the other^ than to refer it 
to the larger quantity of air con^ned with the metal in the 
foroier of thefe two laft experiments* 

EXP. IV. The above light day or a(h*c<Aouttd pow^r, 
ol)tiEiined in the laft experiment by calcining together anti- 
mony and bone^ bettig expofed to varioua degrees of €re from 
20'' to 165^ of WxDGWooD^s pyrometer, in clofe crucibles^ 
was not at all increafed in weighty but generally loft about 5 
fer cent, when a pretty large quantity, as a pound, waa in the 
veiieL A part of this lofs muft be referred to the adhefion or 
vitrification of the charge ^th the iides of the crucible, zxA 
part to the deficiency of the bone itfelf, as above lhewn> hf 
further expofure to fire. I am fenfible, that in experiments of 
this nature all calculation rouft necefiarilyi to a certain degree. 
Vol. LXXXL A a a be 



354 ^^> Pe A Rsos's E^perimnts and Ohfervaiions 

be vague; yet it may be of fome application to obierve# that 
the proportiou of antimonial calx, eftimated to be contained in 
LiLE*s Powder or Puhis antimonialis^ and Jamks's Pow- 
der, p. 343. from the analyfis of them, does not differ more 
confiderably from the proportion of this calx than may, per- 
haps, be reafonably expeded.on calculattoii from thefe four laft 
experiments ,to cxift in them : for 70! parts of antimonial 
calx, p. ^s^' ^^ 54i P^'^^^ P^ bone-a(hes, p. 351. is as about 
56,4 parts of this calx to 43,6 parts of calcined bone; and, 
on analyfis, Jamss's Powder afforded ^V ^ antimonial 
Ctilx, and ^4^ of phofphorated lime, or nearly ib, p. 343. 
allowing for the wafte. 

£xp. V. This experiment ihewsdthe degree of fire neceiHuy to 
render the antimony calcined with bone df a. white oadour; 
and that this whitenefs iloes oot depend on the air, but OA the 
fire. . i . . . 

{a) 1 500 grains of the^ calcined mixture of antlmcmy and 
bone, Exp. 3. were kept, red hot. in a. cloie vefibl for 
half an hour. On coolings . I found the powder changed 
from a cineritious or cUy colour' to a whiti(h coloutftwitk 
a (hade of yellow* i The fides of the crucible were not glazed. 
The pyrometer in the middle lof the powder had contk£led to 
40^ This powder was muoh inferior ki whitenefs to J-aMbs's 
Powder, being m«ch yellowert 

(Ji) Another parcel of jht fame powder, Exp. 5. was 
expofed in the fame manner, biiit to a greater degtise of fire, 
in which the crucible waa almoft white hot for half ^n hour* 
After cooling, the. powder was fiaund changed to* a loofely 
cohering, fnpw* white, heavy mafs, and the fides of the* cru- 
cible were covoced with, a yellow glaze. This mafs^ which 

.. - ' »'was 



m'the Compoftion of' ] AMi%* i PowAr: ^ 35^ 

was cafily detached from the veflel, was found covered with i 
yellow vitreous coat over the whole furface of it that had been 
in contaft with the crucible. In the- white folid, on breaking 
it, friafiy argentine y^/Vi^/^ ivere feen. The pyrometer ufed in 
all thcfe experiments indicated 71^. 

(0 '5^^ grains of the fame parcel, Exp. 3. were expofed 
in an open crucible to the fire of a melting furnace ; no 
fumes arofe till the crucible began to be altaoft white hot. 
After inverting another crucible, with a fmall hole in its bottom, 
the fumes continued to afcend at times through the aperture 
for a quarter of an hour. The crucible was then taken out of 
the fire, and on cooling a wbitijh powder was found, but no 
glazing, and the pyrometer indicated 28°. On again expofing 
this crucible with one inverted over it in the melting furnace, 
but to a greater degree of fire, ftill more fumes arofe ; button 
cooling, the charge was ftill in the ftate of a powder, though 
Hjobitcr than before; and thclnfide of the inverted crucible was 
covered with filvery* particles, and the hole of it was furrounded 
with argentine ^/c^Aj, in a ftellated form. The pyrometer 
indicated 39**. On reducing a little of this powder to a greater 
degree of finenefs, it was as white as James's Powder, with a 
yellowifli caft like it, but inferior in whitenefs to a fpecimen of 
PuVoh antlmomalts. This crucible, containing its charge, with 
a cover clofely luted on it, was put again- into the fire, which 
was raifed much higher than before; and, after being expofed 
in it twenty minutes, the powder in the crucible became a 
loofelyxohering folid, z%wBittasfnoWj with a vitreous yellow 
coat, as before obferved ; the infide of the crucible was glazed 
and cqycrecj with fpicula* .The pyrometer-piece in. the middle 
of thcr powder was alfo covered with t. yellow coat, but not 

A a a z glazed. 



35^ Dr. l^BAtstiiH\\Es(pmmmts}at$d Oifirvatsans 

glated^ .floid.ieiiatilicabedi^i^. This kxifely cabermg iblid 
beiog. pulvcfisod. afforded ' a tt;;6/V#r powder than James's 
Powder. 

(d) The ccuctblct with its charge {A)f having a coirer 
well luted on tt| was again ^ut into the furnace, and the 
fire raiCed to ahi>ofl:.as great a degitee as I was able* This 
iotenfe heat wasr kept up above an hour* After coolingt a 
whitQ hard folid cpafs was found within the crucible. On 
breaking the vefleU to detach from it the charge, this folid 
mafs was found as hard a& marble^ and to have received its figure 
from the crucible. Its furfiice waa covered with a yellow vt^ 
treous coat, and the whole infide of the veflel had a beautifi|l 
gold-coloured glaze with many argentine ^Vir/j. The pyro* 
met^r piece in the middle of the charge was alfo covered with 
a fine. yi!:llow glaze^ and indicated I66^ This folid, hard mafs 
weighed only 21 grains lefs than Before the experiment, thoogh 
the whole infide of the crucible was* glazed, and had fhining 
fpicuh t^pcm it. A. piece of thishard mafs being pulverized^ • |t 
afforded a whiter powder than. James's powder is in generaU' ( 

£XP.;V.i4 zooo grabs of coatfely powdered antimony, mixed 
with 1105'gr^na of calcined hart*s horn in powder, weite 
calcined .firfl in an dpen ve/Tel, and then expofed to a great^d^Mb 
of fire in a clpfe vd&el, aa in the above experiments with bone^ 
(havings, £jfp» 3. and 4; The calcinatbn of this txxish 
ture iu the open veifel afforded 2550^ grains, of a lefs'whsiii|i 
and rather yellowifh powder,. infteadt)f a light afh-colour,*as with 
bomq. A>avings> :£}(ps 3* p^ S53-S ^ndby the fecond, and even 

* In aoother crxperiment of this kind 2400 grajns of antifnoQ^ and I CQQ 
graiDS of calcined bone afforded 3450 grams of yetlowifli light-brown powder* 
In a tbii^ trial, 600 grains of antindony and 4OO 'grains of calcined lx>be gave 
S50 grJuoB of 'jrellowifli bMira,p6wite. > .^ ' . ^ t !>. •« 

repeated 



repeated MpoTure to iire, it never could he :made jq^ite fo wiilfal; 
but feemed more/mcUned to melt thaD.'tbe!>powderi prj^rtti 
ivith unburnt bone. In other refpe^ls the effefts of fire Alteife 
apparently the fame,- or^ nearly fOf as in the experiitiVnts 
with bone ihaviogs, Exp. 39 4* ; for though the lofs of 
weight in this experiment, reckoning that of the antiMony at 
29I per cent.^ and that of the bone aihes at 2i per cent. Ihould 
have left 2483 only, inftead of 2550 ; yet, in othef fimilnr 
experiments, the produd correfponded nearer to « this' dalcula^^ 
tion, and the lofs was ibmetime&.left both df the antimony 
and bone calcined feparately. Some of the peribns who pre^ 
pare the Puhis antinummHs fay^ that the whiteft colour is 
obtained by fir A: boiling the bone Ihaviugs to diiiblve^ their 
mucilage, and. th«i calcining them with antimony as above 
ihewn. Mr. LiL£*8 receipt direda. preyious* decodlion: of tbo 
hart's hom. > 

It will not be difficulty from thefe experiments^ to giv^ a^ 
probable reaibn for the James's Powder being generally of a 
yellowifl) caft, and for difierent parcels of it, as well as of the 
Pulvis antimoniaKs^ being generally of dif&rent degrees of whiter 
nefs and fliades of yellow. The colour of this preparation is^ 
however, a very delicate one. I once direfled a perfon to^ 
calcine together antimony and bone^fhavings, in the lifdali 
manner, to that ftate in which the white powder may^ ba 
produced by a due degree of fire; but, inftead of a tfn6w<*whke 
mafs, I could 'not by any degree of fire obtain . any* colours* 
but a dirty whitiih or light ftone; colours though repealed 
calcinations were employed. The reafon. of the failure 
was, that the earthen difli had been broken, during the* 
calcination, and a few very fmall pieces of it hi^d fcal^ o0^ 
and being jmixed with the powder occaQpMd tbia dii^ppoiiitiiient* 

witht 



358 Dr. PEARSMf^s Ro^perhAmts ^Hd bl^ifkmibrii 

with refpefl: to colour^ The fame difappointment has been ^f5 
occafioned by ufing a rufty iron rod in calcining the mixture. 

The bone-a(hes procured^ from the fal ammoniac and 
fpirit of hart's horn manufaftoriefe, frequently failed in pro^ 
ducing a white powder; and- fo did fometimes the bone-afhes, 
called prepared, hart's horn, foW by the druggifts. Even after 
a fine white coloured mafs had been made, if it was pulverized 
in an iron mortar that had extremely little calx upon its furface^ 
or dirt, the powder was not white* 

The yellow coat and. glaze on th^ fides of the crucible and 
furface of the calcined mixture of bone and antimony^ in thefe 
experiments, is to be afcribed rather to the fufion of the clay 
of the crucible with the dntimonial calx, than to the greatet 
degree of fire in the part of the crucible in which it takes place i 
or than to the cak^ of iron and (ilicequs earth of the vefTel t 
becaufe the fame yellow coat and glazing are produced on the 
Wedgwqiod pyrometer pieces, which are placed in- the middle 
of the charge, and where the degree of heat cannot be fo great 
as nearer the fide of the crucible, and yet a fnow-white mafi 
k produced between thefe clay^-pieces and the fides of the 
crucible. Ttds effed: of clay, in forming i yellow coafc and 
glaze, is fhewu by the obfervation of what happens when the 
calcined mixture is put into a Wedgwood's crucible, which is 
made of much purer clay than otheir vfefTels of th?s kind, and 
when it is fct in a larger HefSan crucible with tMtf fpacc bc-^ 
twixt the two veflth filled with the fame calcined ^ mixture. 
After expofure to a fufficient degree of fire, vi%. about 120^ of 
Wbdgwood^s fcale, the infide and outfidie of the inner cru* 
-cible will be covered with a yello^ vitfeous coat and glaze as 
well as the infide of the outer crucible in contad with the 
charge^ while the *eft of the matter within thefe V^is ii-bf 

a fnowy 



^tHe ^mpbjiihn ^^ Jameses P&tvder. ^59 

i fnoWy whitenefs. This yellow coat is one reafon for the 
powder being of a (hade of yellow in fome fpecimens. 
' Siippofing the fuiibility of the antimbnial calces to be dimi* 
nKhed the more they art calcined ; the following experiment 
ihews,- that the antioionial calx in James's Powder is more 
calcined than that in Exp. 2. ' 

* EX*i Vli. 7oi graihs bf iialclned antimony*, as prepared in 
Exp. 2; triturated With ^^i' grains of calcined bone, formed a 
powder of a blmfhcafty WRxch being expofed in 'a clofe cru- 
cible '£>r half ah hduf, in a .melting fuhiace, the degree of 
fire ih'tyhlch was i'2b* of M^Kdq wood's fcale, it was found 
melted into a vitreous, pale bluifli mafs ; and the iniide of the 
cruciblb was glazed yellow, with red fireaks^ ai^d had argen- 
tine j;^»/ii adhering to it. ' 

* ixpw vifi. 800' griidds o^ the cftlcin^ iantimony of 
Exp. 2. iR^ere calcined for clight hotirs m a di(h; as in 
ihakirig Lilb*s Powddi-y bf ftirrihglt cotiftantly, ahdiceeping 
tlie botfom 6f the veiled l^ot duriMg the whole fime; the 
two laft hours alio the whole of the powder was kept Kd hot* 
On )co6liog^ this calx Wasfin'impalpable light-browh powder. 

• (a) 100 graih'9 of rhi6 calx^ triturated Urith ail e^ual quan- 
tity of calcined hart's hotn, formed a powder very unlike 
jAMSs's Powder^ f&t it was <if a Ught-bro^n'colour* On expo- 
£dg it to about 1 ao^ of fire it melted into a yellow opaque mafs. 

(3) Th^ remaining 700 grains of the calcined antimohy of 
this experiment were expofed to fire arid dir as before f6r eight 
hours longert and kept red hot a great patt of the time ; but 
the cak^be4:ame vety little lighter cdloured than before. 

* (r) 100 grains of this calk laft menhoned (^), triturated 
with Mtnuth calcined hart'a horn^ being expofed to the degree 
erf ^reufuialiy applied in musing the Puhis Jlntimnialis^ in a 

6 clofe 



^$0 Dr. Pe axsok's Experimmtf and Obfirvatms 

^ofe veflely the mixture xnelted partially into a greyifii 

mafs. 

.(^) 150 graius of the calcined antimony (i) of this experi* 
ment were mixed with an equal weight of calcined hart's hom» 
This mixture was raked about in an earthen di(h for an. hour, 
during a great part of which time it was red hot. On coolifigi 
the powder was evidently lighter coloured than before <his cal- 
cination. It was then expofed in a clofe crucible to a white 
heat for half an hour ; and, after cooling, a loofdy coheriog 
white folid^ with a vitreous yellow coat, was found, Uttle 
inferior in whitenefs, and otherwife refembling James's 
Powden 

(e) 300 grains of the calcined antimony (i) of this experi- 
cnent were raked about in an earthen di(h for an hour, a great 
part of which time they were kept red hot. On coolbg, the 
calx was found of the fame colour as before ; and after ex- 
poiing it in a clofe crucible in the melting furnace to almoft a 
white heat for half aa;.hour, it was obfcrved to have beea 
melted into a yellowifli mafs. 

It feems at leaft very probable, from this experiment, that 
mo degree or duration of fire, applied In op6n or clofe veflels to 
antimony alone^ can produce a calx of the (ame kind as that ia 
Jameses Ppwder : nor, perhaps, can fuch a powder be 
pompofed by fire applied, in do& vefiiels, to calx of anti- 
mony mixed with calciued bone; but if antimony duly 
calcined be mixed with calcined bone, and expoied to 
air, in a due degree of fire, for a fofficient length of time, 
and then a ftill greater degree of fire be applied to it in 
c]0k veflels, fuch a compound may be formed as jABfBs's Pow- 
der. This experiment alfo proves, that the fulpbur in anti« 
mopy is no ways necefikry to the formation of this compound, 
a The 



M tbi Cmp^kn of Jam es^s Powder. gf i 

The manner in which air and fire aft upon the anttmouial 
calx and pbofphorated lime, I (hall venture to coojedure. 

It is probable, that the calx of antimony and pbofphorated 
lime combine with each other, i. Becaufe it requires the ap- 
plication of heat and air for a (horter fpace of time to feparate 
the fulphur from a given quantity of antimony mixed with 
bone-alhes than to produce this eiFcift on antimony iy itfelf: 
nor can the fpeedy calcination of antimony with bone*a(hes be 
explained by fuppofing that the antimony can then bear more 
heat without meltmg ; for the difference in the degree of heat 
applied in the two cafes is not, ap)[)arently, fufficient to account 
for the difference of the times required for defulphu rating the 
anticnony. z. Becaufe it appears, that heat, applied to anti- 
mony in a coofiderable variety of degrees, and air for various 
fpacGS of time, formed a calx very different in colour, fufibi- 
litVft and other chemical qualities, from that produced by cal- 
cining this metallic fubOance with hene-aflies. The ftrongeft 
confirniatfon, perhaps, of the opinion that the antimonial calx 
and pbofphorated lime are chemically united together is, that, 
however long the calcinatkm of the antimony and bone-a(hes is 
continued in the open veffel it will only produce precifely the 
iaa>e fubftance^ with refpe£t to chemical properties, that is 
produced the moment the fulphureous fumes ceaie. 

But why is a fnow-white powder produced by expofing a 
mixture of calcined antimony and bone-afhes to air and fire for 
a due length of time, and tfhen applying a greater degree of fire 
in clofe veflels, whereas no fuch white powder is formed by a 
mixture of any calx of antimony and bone^afhes, expofed to any 
degree of fire in clofe vcflfels, without previous expofure to fire 
and air ? The reafon may be, that in order that the calx (hould 
unite with the pbofphorated lime, it muft be calcined to one 

\oh. LXXXI. B b b certain 



362 Dr. Pearsov^s Experiments and Obfervations ' 
certain degree ; whidh is efFeftcd by expofure to air and fire With 
the bone-afhes when it can part or combine with air, fo as to be 
reduced to that ftate in which it will be duly calcined for union 
with that fubftailce, which could not happen in clofc veflels* 

If it be objefted, that this explanation does not account for 
the wbitenefs of this preparation, which is only produced by a 
white heat, and to which air is not neceffary, the difficulty 
will be removed by confidering that this whitenefs may be in- 
duced without any chemical alteration effeded by the fire : for, 
after the firft calcination in the open veffel, it feems to adt, prin- 
cipally, in the fame way that it does in making grey- coloured 
bone-aflhes, or imperfe6lly burnt bone, of a fnowy whitenefs, 
namely, by totally deftroying matter extraneous to the phofpho^ 
ric felenite. Fire alfo, in many inftances, alters the colour of 
bodies without occafioning any change in their compofition ; 
and, perhaps, the change of the light clay or cineritious pow- 
der, formed by the calcination of antimony and bone-a(hes in 
open veflels, to a fnowy-white fubftance by further expofure to 
fire, depends in part upon its increafe of fpecific gravity or 
other mechanical efFefts of fire. A flriking example of the 
power of fire to change the colour of bodies, by merely in- 
creafing their fpecific gravity, is afforded by the operation of 
quartation, in which procefs, the filvcr being parted, the gold 
is left of the colour of copper ; but, by expofure to a due 
degree of fire, it is changed to its well known yellow colour, 
without undergoing any alteration except an increafe of fpe- 
cific gravity. 

To elucidate the nature of the infoluble and infufible part of 
James's Powder, I made the following experiments, in which 
I particularly had in view to determine whether feveral anti- 
monial calces be wholly foluble iti acidst 

£XP« 



en the Cempqfitton of James's Powder. 36^1 

BXPt IX. (^) Needle-like cryftals of Algaroth powder dif- 
iblved readily and totally in about thirty times their weight of 
marine acid. 

(A) Part of the fame parcel of cryftallized Algaroth pow- . 
d?r was calcined for above two hours, during which time it 
was expofed to as great a heat as it would bear without melting, 
and during which time it wasconftantly raked about. Nearly 
half of this calcined calx readily diiTolved in marine acid, 
and by boiling the remainder in a proportionally much greater 
quantity of the fame acid, great part of it was diflblved, and 
the fmall part which ftill refifted folution could not be diflblved 
in above lOO times its quantity of hot aqua regia. This indif- 
foluble part afforded regulus with tartar by means of heat 
applied with the blow- pipe. 

. (c) White flowers of antimony generally left a refiduum 
that was either infoluble, or diflblved with great difficulty, and 
in a fmall proportion, in marine acid or aqua regia ; yet this 
refiduum was reducible. Some parcels of this calx tota/iy 
jdifliblved. 

(d) A little of the antimony, long calcined in a former 
experiment, and afterwards melted into a yellow mafs, 
Exp. 8. (tf), would only partially diflblve in marine acid 
and aqua regia ; but the copious refiduum it left was reduced. 

(^) Equal weights of cryftals of Algaroth powder anc) cal- 
cined bone mixed together, diflblved totally and readily in ma- 
rine acid* This (hews, that difengaged phofphoric acid does 
not precipitate antimonial calx wrhen marine acid is prefent. 

(J') The calx antimonii nitrata of the Edinburgh Difpenfa- 
tory, argentine flowers of antimony, hyacinthine glafs of 
antimony, and calx precipitated from antimonial tartar by alkali 
of tartar, all diflblved readily and wholly in marine acid ; but, 

B b b a (iO Dia- 



{^J iDiaphorctk atitimony left a 1-fefidOum which mited with 
ttiH\tr formtd metallic grams under the' flame applied by means 
of the blaw-pipe» ^ • 

'{jh) Any of the above ibluble ahtimonifll Calces by farther 
caltih'ation with ait and fire become more difficultly Ibluble, 
or partly indiflbluble. 

The next experiments were made principally for the pWpoft 
of knowing .whether antimony calcined with Titridlic "fele- 
nite, calcs^reous earth, and filiceous earth, would afford lh6 
fame fort of calx as Sntimony calcined with bone-a(hes. 

EXP. X. 1500 grains of well burnt and dry plafter of Paris, 
mixed with as much pulverized antimony, were calcined toge- 
ther in the fame manner as the mixture for making Lilb's 
Powder, Exp. 3, In half an hour the fulphureous fumes 
difappeared ; after calcining half an hour longer in a heat 
that kept the bottom of the difli red hot, the mixture was 
of a rcddifli brown or copper colour, and after cooling 
weighed 2520 grains. Suppofing, therefore, the whole defi- 
ciency of weight in this experiment to be from the fulphur 
carried off; and fuppofing the quantity of air combined with 
the metal to be the fame as in Exp. 2. the lofs of weight 
viz: 32 per cent, is more than would have been expcdled ; but 
as iti experiments of this nature it is not perhaps poflible to 
repeat them under precifely the fame circumftances, the dif- 
ference of 2 1 per cent, deficiency more than would have been 
calculated, may more reafonably be afcribed to the fublimation 
of antimony than to other caufes. By expofure t6 70** of fire 
ill a clofe crucible, this calcined mixture changed to a pale 
ftraw-coloured powder, and the fides of the veflel were glazed 
yellow. The change of colour was the fatae ih an open veffel 
in do** of fire. 

Though 



Though it is prol?able» ffqmtliii? expariment, thattjhtm-e is 
an .afikity between aatimoqial calx and vitriolic felemjtt, it is^ 
plain that the coaipound is very different ifrom James's Pbwder, 

The next experinoent with chalk aiid. antimooy, which Dn 
B£.AGDXN had the goodnefs to fuggeft, would lead to feveral', 
conclufionSy but I (hall only take notice of the compolitioiit 
produced. 

Exp. xr. 1 200 grains of antimony were mixed with 800^ 
grains of well wa(hed, dried, and pulverized chalky and cal^ 
cined as in making Lils's Powder. In lefs than an hour the 
findl of fulphur difappeared ; after which the mixture was 
calcined half an hour longer. It af&rded a lighter clay« 
coloured powder than the calcination of antinu>ny with bone* 
alhes; and weighed 1800 grains. By ezpofure to 100^ of fire 
this powder changed to a dirty white colour. On examination,, 
inftead of aerated lime or chalkj there was found vitriolic fele* 
nite^ part of which was probably combined with the antimo* 
nial calx 1 for, by means of boiling water repeatedly applied 
till the lixivium did not become turbid with muriated ba* 
ry te$ nor acid of fugar, I could only obtain 1 2 per cent, of 
vitriolic (eleuitet mixed with a little autimonial calx ; but by 
means of nitrous acid I feparated 45 per cent, of this feleuiteg^ 
with fcarcely any antimonial calx in it. The refiduum, after 
this (blution in nitrous actd^ was calx of antinxHiy with a little 
vitriDlic felenite iieemingly vitrified. Accordingly the compo* 
fition may be dated to confifl: of 1000 parts of antimonial calx, 
and 950 parts of vitriolic felenite which I infer from the quan- 
tity of felenite diflblved by the nitrous acid, and efiimated to 
remain united to the calx ; and from the following calcula- 
tion of the proportiiNi of thefe two ingredients formed in the 
experiment. 

2 Anti- 



366 Dr. VE,kTi%0Vi\ Experiments and Objervations 

Antimony. Sulphur. Air. f - « 

1 200 - 300 4- 1^0 = 1000 Antimonial calx. 

Calcar. Aerial VitrioUc 
earth. acid. . acid. 

800 — 300 + 450 = 950 Vitriolic felenite. 

Lofs by fublimation aiid wafte 150 

1800 

With regard to the nature of this calx, the grcateft part of 
it readily diiTolved in marine acid; and part of what then re- 
mained was alfo diiTolved, but with great difficulty and very 
(paringly; a minute quantity refifted folution entirely. 

EXP* XII. 600 grains of coarfcly powdered antimony were 
mixed with 400 grains of purified white fand, and calcined as 
in making Lile's Powder. The fmell of fulphur continued 
for on^ hour and a half, and the mixture was calcined for half 
an hour longer. On cooling, a brown powder was obtained 
which weighed 820 grains, and expofed to 100** of fire, melted 
into an irregularly figured, blackifh mafs, full of cavities. 

In this experiment the lofs of weight correfponds nearly to 
that in experiments above related, viz. thofe in which the 
deficiency of weight after calcining antimony alone was about 
^9§ p^^ <^^^f^ The much longer time required in this experi- 
ment for carrying off the fulphur than in the calcinations with 
^one-a(hes, gypfum, and chalk, perhaps is owing to there 
being no affinity between autimonial calx and (iliceous earth. 

I beg leave to mention one more experiment relative to 
James's Powder. 

EXP. XIII. A medicine is fold by F. Newbery, under the title 
of" Jameses Powder for Horfes, Horned Cattle, Hounds, &c." 
It is a light clay-coloured, gritty, taftelefs fubftance, in which 

arc 



on the Compofitioit of James's Powder. ^^y 

are feen {mdM/plcuJa. It appears to me to be nothing more thaa 
James's Powder for Fevers, or Lile's Powder above-men- 
tioned, made by calcining antimony and bone-a(hes together in 
open veflTels ; becaufe, ift, by expofure to a white heat in clofe 
veffels, it turns as white as James's Powder. 2dly, It dif- 
folves partially in nitrous acid ; and the remainder diflblves 
partially in marine acid. The nitrous folution contains 
phofphoric acid and calcareous earth ; and the muriatic folu- 
tion affords Algaroth powder. 

From the whole of the above analytical experiments \x, appears : 

I. That James's Powder confifts of phofphoric acid, lime, 
and antimonial calx ; with a minute quantity of calx of iron^ 
which is confidered to be an accidental fubflance. 

Z. That either, thefe three eiiential ingredients are united 
with each other, forming a triple compound, or, phofphorated 
lime is combined with the antimonial calx, compofing a double 
compound in the proportion of about 57 parts of calx and 43 
parts of phofphorated lime. 

3* That this antimonial calx is different from any other 
known calx of antimony in feveral of its chemical qualities. 
About three-fourths^ of it are foluble in marine acid, and afford 
Algaroth powder; and the remainder is •hot foluble in this 
iQenftruum, and is apparently vitrified. 

From the preceding,^«/Art/c experiments it appears, that by 
calcining together bone-a(hes, that is, phofphorated lime, and 
antimony in a certain proportion, and afterwards expofing the 
mixture to a white heat, a compound was formed confifling of 
antimonial calx and phofphorated lime, in the fame proportion, 
and poffeffing the fame kind of chemical properties, as James's 
Powder. 



[ 3«i» 1 



XXn. An Account offimi cbemical Expirimewis m Tabaflioer. 
By James Louis Muciet Efq. F. R. S. 



Read July 7, 1791. 

THE Taba(heer employed In thefe experiments was that 
which Dr. Russell laid before the Society, as fpeci- 
mens of this fubftancei the evening his Paper upon the lub- 
jeft was read •• 

There were (even parcels. 

N® I. confifted of Tabaflieer extrafted from the bamboo by 
Dr. Russell himfelf. 

N® 2. had been partly taken from the reed in Dr. Rus- 
sELL^s prefence, ^nd partly brought to him at different times 
by a perfon who worked in bamboos. 

N"" 3. was the Tabafheer from Hydrabad ; the fineft kind of 
this fubftance to be bought. 

N** 4, 5» and 6. all came from Mafulapatam, where they 
are fold at a very low price. Thefe three kinds have been 
thought to be artificial compofitions in imitation of the true 
Tabafheer, and to be made of calcined bones. 

N'' 7. had no account affixed to it. 

The Tabafheer from Hydrabad being in the greateft quan- 
tity> and appearing the mofl homogeneous and ^pure, the 
experiments were begun,. and principally made, with it. 

* Sec Phil. Trant Vol, LXXX. p. 283. 

Hyirahad 



Mr. Macii^s Acc$unt^ Uc. 369 

HydrahadTahJbeer. (N** 3.) 

§ L (A) This, in tts general appearance, very much refem^ 
bled fragments of that variety of calcedony which is known to 
mineralngifls by the name of Cacbolong. Some pieces were 
quite opaque, and abfolutely white; but others poifefTed a 
fmall degree of tranfparency, and had a blui(h caft* The 
latter, held before a lighted candle, appeared very pellucid, 
and of a flame colour. 

The pieces were of various fizcs; the largeft of them 
did not exceed two or three tenths of an inch cubic. Their 
ihape was quite irregular; fome of them bore impredions 
of the inner part of the bamboo againft which they were 
formed. 

(B) ThisTabaftieer could not be broken by preflure between 
the fingers ; but by the teeth it was ea(ily reduced to powder. 
On firft chewing it felt gritty, but foon ground to impalpable 
particles. 

(C) Applied to the tongue, it adhered to it by capillary 
attraction. 

(D) It had a difagreeable earthy tafte, fomething like that^ 
of magnefia. 

(£) No light was produced either by cutting it with a knife, 
or' by rubbing two pieces of it together, in the dark; but a bit 
of this fubftance, being laid on a hot iron, foon appeared 
furrounded with a feeble luminous aureole. By being made 
red hot, it was^ deprived of this property of (hining when gently 
heated ; but recovered it again, on being kept for two months. 

(F) Examined with the microfcope, it did not appear dif« 
ferent from what it docs to the naked eye. 

Vol. LXXXI. C c c (G) A 



^fCk Mr^ Macis'8 Ac€duni of 

(G) A quantity of this Tabaihcer which weighed 75,7 gr. 
in air, weighed only 41.1 ^r, in diftilldd water whofe tempe- 
rature was 52.5 F, which makes its fpecific gravity to be very 
nearly = 2. 188. 

Mr. Cavendish, having tried this fame parcel when become 
agSiin quite dry, found \X% fpecific gravity to be = 2.i6f • 



Treated with water. 

§ 11. (A) This Tabafheer, put into water, emitted a number 
of bubbles of air; the white opaque bits became tranfparesU 
in a fmall degree only, but the blui(h ones snarly a& much 
fo as glafs. In this (late the different colour produced by 
reflefted and by tranfmitted light was very fenfible. 

(B) Four bits of this fubftance, weighing together, wbik 
dry and opaque, 4.1 gr., were put into diftilied water, and let 
become tranfpareut ; being then taken out, and the unab- 
forbed water haftily wiped from their furface, they were again 
weighed, and were found to equal S.2 gr. 

In the experiment § I. (G), 75.7 gr. of this fubftance ab- 
forbed 69.5 gr, of diftillcd water. 

(C) Four bits of Tabaflieer, weighing together 3.2 gr. were 
boiled for 30^ in half an ounce of diftilled water \i\ a Florence 
fialk, which had been previoufly rinced with fortie of the fame 
fluid. This water^ when become cold, did not fliew any 
change on the admixture of vitriolic acid, of acid of fugar, 
nor of folutions of nitre of filver, or of cryftals of foda ; ytU 
on its evaporation, it left a white film on the glafs, which 
could not be got o£ by walhing in cold water, nor by hot 

marine 



Jome chelnical ExpefmtMs m Tabaflieer. ^^i 

rttA\if\t^z\Ai btit which was dJfchafged b^ warm fcauftic vege- 
table alkali, and by long ebullition in water. 

Up6!> tlidfe bits of Tabaftieer, another half ouncfe of 
diftilled w^ter Was foored, anid again boiled fbr about h«1If aftl 
hoo^« This Rafter alfo on evaporation left a whit6 film on the 
glafe velf^l, (lA^War to the above. The pieces of Tabafbeer 
having been dried, by expofure to the air for fome days in a 
^rarm room, were found to have loft one-tenth of a grain of 
tbei'r weight. 

To affcertain whether the whofe of a piece of Tabaflieer 
could be diffolved by boiUng ii^ water, a little bit of this fub- 
ftatice^ weighing tfhree-tenths of a grain, was boiled iti 36 
ounces of (oft water for neai^ five hours confecutiv'ely : bud 
being afterwards dried and weighed, it was not diminiflied iti 
^jmntky, ner wa6 it deprived c^ itii tafte. 



l^itb vegetaile colours. 

§ Itr. Sonie Tabalheefr,^ reduced to fine powder, Viras'bdiled' 
ftyr a' confiderable time in' infufions of turnfolc, of logwdod,' 
a'hd of dried' red' cabbage, bub produced not the leadft ehahgfe iii^ 
iliy^bne of thertt, 

Jithcfirex 

f IV: (A): A piece of this Tatafhe^r, thrbv^ii intoa i^ed Hdt^ 
crucible, did not burn or grow black. Kept red hdt^ for fbnit 
time, it underwent no vifible change ; but When' cold, it wa^ 
harder, and had entirely loft its tafte. Put into' ^ater it 

C c c a grew 



37^ Mr. Macie^s Account of 

grew traoiparent, juft as it would have done^ had it not been 

ignited. 

(B) 6*4 gr. of this fabftanccy made red hot in a crucible^ 
were found, upon being weighed as foon as cold, to have loft 
two-tenths of a grain. This lofs appears to have arifen merely 
from the expulfion of interpofed moifture; for thefe heated 
pieces, on being expofed to the air for fome days, recovered 
exaftly. their former weight. 

(C) A bit of this fubftance was put into an earthen cruci* 
ble, furrounded with fand, and kept red hot for fome time; 
when cold, it was ftiil white, both exteriorly and interiorly. 

(D) Thrown into fome melted red hot nitre, this fubftance 
did not produce any deflagration, or feem to fufier any alte- 
ration. 

(E} A bit expofed on charcoal to the flame of the blow-pipe 
did not decrepitate or change colour; when firft heated it 
difFufed a pleafant fmell; then contradled very confiderably in 
bulk, and became tranfparent ; but on continuing the heat it 
again grew white and opaque, but feemed not to fhew any, 
ificlination to melt per fi. Poifibly, however, it may fufFer 
fuch^ a femi-fufion, or foftening of the whole mafs, as takes^ 
pl^ce in clay when expofed to an intenfe heat; for when tho 
bit ufed happened to have cracks,, it feparated during its con- 
tradion, at thefe cracks, and the parts receded from each other 
without falling afunder. 

If, while the bit of Tabafheer was expofed to the flame^ 
any of the aihes of the coal fell upon it, it inftantly 
melted, and fmall very fluid bubbles were produced. That the 
opacity which this fubftance acquires on continuing to heat it 
after it is become tranfparent, is npt owing to the fufion of its 
^ furface 



Jomt chemitalExferiments on Tibafliecr. y^^ 

furface by means of fome of the.alhes of the charcoal fntling 
upon it unobferved, appeared by its undergoing the fame 
change when fixed to the end of a glafs tube^ in the method 
of M. D£ Saussure *. 



§ V. (A) A piece of Tabafheer, weighing 1.2 gr, was 
firft let fatiate itfelf with diftllled water; its furface being 
then wiped dry, it was put into a matrafs with fome pure 
white marine acid, whofe fpecific gravity was 1.13. No efFer- 
vefcefice arofe on its immerfion into the acid ; nor did this 
mendruum, even by ebullition, feem to have any aftion upon 
it, or itfelf receive any colour. The acid being evaporated 
left only fome dark coloured fpots on the glafs. Thefe 
Ipots were dlflblved by diftilled water. No precipitation was 
produced in this water by vitriolic acid, or by a folution of 
cryftals of foda. The bit of Tabafheer waflied with water, 
and made red hot, had not fuflained any lofs of weight. 

The pores of the mafs of Tabafheer were filled with water 
before it was put into the acid, to expel the common air con- 
tained in them, and which would have made it impoffible to 
afcertain with accuracy whether any efFervefceijce was pro- 
duced on its firfl contadl with the menftruum. 

(B) Another portion of Tabafheer, weighing 10.2 gr# 
was boiled in fome of the fame marine acid. Not the leafl 
precipitate was produced on faturating this acid with folution 
of mild foda. This Tabafheer alfo, after having been 

* Journal dc Phyfique, Tom. XXVL p.- 409, . 

boiled 



W4 Aft-. MACifif s Aictunt rf 

bfoUed in water, and dried by expofure for fome days to the air^ 

was ftill of its former weight. 

§ Vi. This fubftance feemed in Uke manner to refift the 
adtion of pure white nitrous acid boiled upon it. 

§ VIL (A) A bit of Tabafhcer weighing 0.6 gr. was digefted 
in fome ftrong white vitriolic acid, which had been made per- 
fedly pure by diftillation. It did not feem by this treatment 
to fufFer any change, and after having been freed from all ad- 
hering vitriolic acid by boiling in water, it had not under^ 
gone any alteration either in its weight or properties. The 
vitriolic acid afforded no precipitate on being faturated with 
ibda. 

(B) Two grains of Tabaiheer reduced to fine powder wers 
made into a paftq with fome of this^ fame vitriolic acid^ and 
this mixture was heated till nearly dry ; it was then digefted ia 
diftilled water. This water, being filteriBd, tafted. ilightljr 
acid, did not produce the leaf): turbtduefs^ vv(i{^ fblutian of fodsi 
and fome of it, evaporated^ left only a faint black; flain on 
the glafs, produced doubtlcfs by thea£Hon:of the vitdolio acid 
on a little vegetable matter, which it had received either frbm 
the Taba(heer» or ftom. the paper. The undiflolved matter 
colkifled, waflied; and dried; weighed 1^9 gr. 

§ yin> 2 gr. of Tabaftieer, reduced to^ne pawdcttv wieire long 
digefted in a confiderajbte quantity of liquidaoid of fugar. The 
t^fte of) the liquor was- not altered:; and. being- fatnrared with a 
fblu^tioQ of cryftals of foda in diftilled' water « it did not afford 
any prcQpitatCu Tber Taba{heer having' been freed: from all 
adhering aetd, by very tareful: ablution with diftilled' water, 
and let dry in the air, was totally unchanged in its ap- 
pearance, and : weighed -i ^98* gr. This Tabafliecr being gra- 
ft dually 



Jhmt cbimic0f EjiperimiMs m T^bafliecr. 375^ 

dually heated till fed hot, did not become in the leaft black, 
or lofe much of its weight, a proof that no acid of fugar had: 
fixed in it. 



IFitb liquid aikalies. 

§ IX« (A) Some liquid cauftic vegetable alkali being heated, 
in a phial, Tabaflieer was added to it, which didblved very 
readily, and in confiderable quant tty« When the alkali would 
not take up any more, it was fet by to cool, but was not found 
next morning to have cryftallized, or undergone any change, 
though it had become very concentrated, during the boiling, 
by the evaporation of much of the water. 

(B) This iblution had an alkaline tafte, but ieemingly withi 
little, if any, caudicity. 

(C) A drop of it changed to green a watery tiu€kure of 
dried red cabbage. 

(D) Some of this fbltition was expofed in a (hallow glafs 
to fpontaneous evaporation in a warm room. At the end of a* 
day or two it was converted into a firm, milky jelly. After a 
few days more, this jelly was become whiter, more opaque, 
and had dried and cracked into feveral pieces, and finally h be* 
came quite dry, and curled up and feparated from the glafs. 

The fame change took place when the (blution had been di- 
luted with feveral times its bulk of diftilled water, only the 
jelly was much thinner, and dried into a white powder. 

Some of this folution, kept for many weeks in a bot- 
tle clofely flopped, did not become a jelly, or undergo any 
changei 

(E) A. 



376 Mr. Maci£*s Account of 

(£) A fmall quantity of this iblutioti was let fall into a 
proportionably large quantity of fpirit of wine, whofe fpedfic 
gravity was •838. The mixture immediately became turbid^ 
and, on {landing, a denfe fluid fettled to the bottom, and 
which, when the bottle was hadily inverted, fell through the 
fpirit of wine in round drops^ like a ponderous oil. 

The fupernatant fpirit of wine being carefully decanted ofF, 
fome diftilled water was added to this thick fluid, by which it 
was wholly diflblved. This folution, expofed to the air, 
fhewed phaenomena exa6tly flmilar to thofe of the undiluted 
folution (D). 

The decanted fpirit being alfo left expofed to the air in a 
ihallow glafs veflTel, did not, after many days, either depofit a 
fenfible quantity of precipitatet or become gelatinous ; but bav« 
ing evaporated nearly away, left a few drops of a liquor which 
made infufion of red cabbage green ; and, on the addition of 
fome pure marine acid, effervefced violently. No precipitate 
fell during this faturation with the acid; nor did the mixture 
on {landing become a jelly ; and on the total evaporation of the 
fluid part, a fmall quantity of muriate of tartar only remained. 
The fpirit of wine feems, therefore, to have diflblved merely a 
portion of fuperabundant alkali prefent in the mixture, but 
none of that united with Tabaflieer. 

(P) To different portions of this folution were added 
fome pure marine acid, fome pure white vitriolic acid, and 
fume diftilled vinegar, each in excefs. Thefe acids at firfl: pro- 
duced neither heat, efFervefcence, any precipitate, or the leaft 
fc^nfible effedl, except the vitriolic acid, which threw down 
a very fmall quantity of a white matter ; but, after {landing 
fome days, thefe mixtures changed into jellies fo firmi that 

the 



the glafles contabing them were invert^ witliMt their 
falling out. 

This change into jelly equally took place whether the mix* 
turei were kept in open or clofed veflcls, were expofcd to the 
]ight| or fecluded from it ; nor did it feem to be much pro- 
inoted by boiling the mixtures^ 

(0) Some folution of mild volatile alkali In dUlilled water, 
being added to fome of this folution, ieemed at the firft inftant 
pf mixture to have no effedt upon it ; but in the fpace of a 
iecond or two it occafioned a copious white precipitate* 

(H) The flakes remaining on the glafles at (D) and (E) put 
into marine acid raifed a flight effervefcencet but did not di(^ 
folve* Thefe flakes, when taken out of the acid, and well 
wa(hed| were found, like the original Tabaflieer, to be white 
and opaque when dry; but to become tranfparent when 
moiftened, and then to Ihew the blue add flame colour, 
§11. (A). 

(1) The jellies (F), diluted with water, and collefted on a 
filter, appeared to be the Tabafheer unchanged. 

§ X. A bit of Tabaflieer, weighing two-tenths of a grain, wa» 
boiled in 1 27 gr. of fl:rong cauflic volatile alkali for a con- 
iiderable time; but after being made red hot, it had not 
fuflained the leafl diminution of weight* 

§ XI. (A) 27 gr. of Tabaflieer, reduced to fine pow^er^ 
were put into an open tin veflel with 100 gr. of cryftals of 
foda, and fome diflilled water, and this mixture was made boil 
for three hours. The clear liquor was then poured off, and 
the Tabaflieer was digeftcd in fome pure marine acid-j aftet 
fome time this acid was decanted, and the Tabaflieer waflie^d 
with diftilled water, which was then added to the acid. 

Vol. LXXXI. D d d (B) This 



2yt Mr. Macie*s Account of 

(B) This Tabafheer was ptit back into the alkaline folutioir^ 
which feemednot impaired by the foregoing procefs, and again 
boiled for a confidcrable time. The liquor was then poured 
from it while hot, and the Tabaflieer edulcorated with fome 
cold diftilled water, which was afterwards mixed with this hot 
folution, in which it inftantly caufed a precipitation. On 
heating the mixture it became clear again ; but as it cooled it 
changed wholly into a thin jelly ; but, in the courfe of a few 
days, it feparated into two portions, the jelly fettling in a denfer 
flate to the bottom of the vefiel, leaving a limpid liquor 
over it. 

(C) The Tabaffieer remaining (B) was boiled m pure marine 
acid ; the acid was then poured off, and the Tabaftieer edulco^ 
rated with fbme difHUed water, which was afterwards mixed* 
with the acid. 

(D) The remaining Tabaflieer colfeded, walhed,^ and' dried,, 
weighed 24 gr. and feemed not to be altered. 

(E) The acid liquors (A and C) were mixed' togetheiv aud 
faturated with foda, but afforded no precipitate^ 

(F) The alkaline mixture (B) was poured* upon* a filter, the 
clear liquor came through, leaving the jelly on the paper. 

Some of this clear liquor, expofed to the air in a faucer, at 
the end of fome days depofited a fmall quantity of a gela- 
tinous matter; after fome days more^ the whole fluid part 
exhaled, and the faucer became covered with regular cryftals 
of foda, which afforded no precipitate during their folution in 
vitriolic acid. What had appeared like a jelly while moift 
affumed, on drying, the form of a white powder. This pow- 
der was infoluble in vitriolic acid, and feemed ilill to be 
Tabafheer. 

Some 



feme chemical Experiments on Tabafhecr. 3;^^ 

Some of this clear liquor, mixed with marine acid, efier- 

vefced ; did not afford any precipitate ; but, on ftanding fome 

days, the mixture became (lightly gelatinous. 

(G) Some of the thick jelly remaining on the filter, being 

boiled in water and in marine acid, appeared infoluble in both, 

aud feemed to agree entirely with the above powder (F), 



With dry alkalies. 

§ XII. (A) Tabaflieer melted on the charcoal at the blow- 
pipe with foda, with confiderable efFervefcence. When the pro- 
portion of alkali was large, the Tabafheer quickly difTolved, and 
the whole fpread on the coal, foaked into it, and vanifhed ; 
but, by adding the alkali to the bit of Tabafheer in ex- 
ceedingly fmall quantities at a time, this fubflance was con- 
verted into a pearl of clear colourlefs glafs. 

(B) 3 gr. of Tabaflieer, reduced to fine powder, were melted 
in a platina crucible with 100 gr. of cryftals of foda. The 
mafs obtained was white and opaque, and weighed 40.2 gr« 
Put into an ounce of diftilled water, it wholly diflblved. An 
excefs of marine acid let fall into this folution produced an 
efFervefcence, and changed it into a jelly. This mixture was 
flirred about, and then thrown upon a filter. The jelly left on 
the paper did not dKTolve in marine acid by ebullition ; col- 
lected, waflied with diftilled water, and dried, it weighed 4.5 
gr. and feemed to be the Tabaflieer unaltered. * 

The liquor which had come through being faturated with 
mineral alkali yielded only a very fmall quantity of a red pre* 
cipitate, which was the colouring matter of the pink blotting 
paper through which it had been pafled. 

Dddz (C)io 



380 iMr*« MAtiB^s As€oum of 

(C) 10 gr. of Tabalhecrt reduced to powder^ were mixed 
with an equal weight of foda, deprived of its water of cry* 
i^allization by heat« This mixture was put into a platina cru- 
cible, and expofed to a flrong fire for 15^ It was then found 
converted into a tranfparent giafs of a (light yellow colour. 
This glafs was broken into pieces^ and boiled in marine acid. 
No efiervefcence appeared ; but the glafs was diflblved into a 
jelly. This jelly, coUeded on a filter, well wafhed^ and dried, 
weighed 7.7 gr- ' 

The acid liquor which came through, on fataration with 
foda, afforded not the lead precipitate ; but, after (landing a 
day or two, it changed into a thin jelly. This colle£led on a 
filter was wafhed with diftilled water, and then boiled ia nia- 
rine acid, but did not diffolve. Being again edulcorated, and 
made red hot, it weighed 1.6 gr. The filtered liquor (B) 
would in all probability have changed fimilarly to a jelly, had 
it been kept. ^Thefe precipitates were analogous to thofe 
§ IX. (I). 

(D) An equal weight of vegetable alkali and TabaAeer 
were melted together in the platina crucible^ The glafs pro- 
duced was tranfparent ; but it had a fiery tafte, and foon at* 
traded the nK>i(lure of the air, and di(!olved into a thick 
liquor. But two parts of vegetable alkali, with three of Ta* 
bafheeri yielded a tranfparent glafs, which was permanent. 

Treutedwlth other Jluxeu 

§ Xni. (A) A fragment of Tabafheer put Into glafs of 
borax, and urged at the blow-ptpe, contrafted very confiderably 
ki (ize, the fame as when heated perfe ; after which it conti- 
nued turning about in the flux^ difTolving with great difEculty 

I and 



fome cbmtcal Experiments on Taba(Iieer. jff j 

w^i veiy flowly^ When the folutioa was efFeaed, the faline 
pearl remained perfe£lly clear and colourlefs, 

(B) With phoTphoric ammoniac (made by faturating the acid 
obtained by the flow combuftion of phofphorus with cauftic 
volatile alkali) the Tabafheer very readily melted on the char- 
coal at the blow-pipe, with effiervefcence, into a white frothy 
bead. 

(C) Fufed, by the feme means, on a plate of platina, with 
the vitriols of tartar and fbda, it appeared entirely to refift 
their aftion ; the little particles employed continuing to revolve 
in the fluid globules without fuftaining any fenfible diminutioa 
of (ize, and the faline beads on cooling aflumed their ufuaL 
opacity^ 

. (D) A bit of Tabaftieer was laid on a plate of filver, and a 
little litharge was put over it, and then melted with the blow* 
pipe. It immediately afted on the Tabafheer, and covered it 
with a white glafly glazing. By the addition of more Jlitharge 
the mafs was brought to a round bead, though with confidera* 
ble difficulty. This bead bore melting on the charcoal, with- 
out any I'eduftioa of the lead, but could not be obtained 
tranfparent. 

(E) The «afe with which this fiibftance had melted witli 
vegetable aflies, led to the trial of it with pure calcareous 
earth,^ A fragment of Taba(heer, fixed to the end of a bit of 
glafs,. was rubbed over with fome powdered whiting. As foon 
as expofed to the flame of the blow-pipe, it melted with confi- 
derable efiervefcence ;. but could not, ^ven on the charcoal, and 
with the addition of more whiting, be brought to a tranfparent 
fiate, or reduced into a round bead 

Equal weights of Tabafheer and pure calcareous (par, both: 
reduced to fine powder^ weie irregularly mixed, and expofed 

ia 



381 Mr. Maci^s Account of 

in the platina crucible to a ftrong fire in a forge for 20^; b\it 

did not even concrete together. 

(F) When magnefia was ufed, no fufion took place at the 
blow-pipe. 

(G) Equal parts of Tabafheer, whiting, and €arth of 
alum precipitated by mild volatile alkali, were mixed in a itate 
of powder^ and fubmitted in the platina crucible to a ftrong 
iire for ao'i but were afterwards found unmelted. 

Examination of the other Jpecimenu 

This parcel contained particles of three kinds; fome white, 
of a fmooth texture, much refembling the foregoing fort ; 
others of the fame appearance/ but yellowifli; and others 
greatly (imilar to bits of dried moulds 

The white and yellowifli pieces were fo foft as to be very eafily 
rubbed to powder between the fingers. They had a difagrce- 
ble tafle, fbmething like that of rhubarb. Put into water, the 
white bits fcarcely grew at all tranfparent ; but the yellow 
ones became fo to a confiderable degree. 

The brown earth-like pieces were harder than the above, had 
little tafte, floated upon water, and remained opaque. 

Expofed to the blow-pipe, they all charred and grew black ; 
the laft variety even burned with a flame. When the vegetable 
matter was confumed, the pieces remained white, and then had 
exaftly the appearance, and pofleflcd all the properties, of the 
the foregoing Tabaflieer from Hydrabad, and like it melted with 
foda into a tranfparent glafs. 



fotm chemical Experiments on Tabaiheer. 383 

NML 

Alfo confifted of bits of three forts, 

{a) Some white, nearly opaque. 

(ii) A few fmall very tranfparent particles, (hewing, in an 
eminent degree, the blue and yellow colour, by the diiFerent 
direction of lights 

(c) Coarle, brownifli pieces of a grained texture. 

Theie all had exa£Uy the fame tafte, hardnefs, &c. and 
fiewed the fame effefts at the blow-pipe, as N° I. 

27 gr. of this Tabafheer thrown into a red-hot crucible,, 
burned with ayellowifli white flame, loft 2.9 gr. in weight, 
aad became £0 finailar to the Hydrabad kind as not to. be diftin>i> 
gui(hed from it,. 

Some of this Tabafheer put into a crucible, not made very 
liot, emitted a fmell fomething like tobacco afhes, but not the- 
kind of perfume difcovered in tharfxx)m Hydrabad, § IV. (E). 

All the pieces of this parcel were of one appearance, and a 
good deal refembled, in their texture, the third variety of N®' 
IL Their colour was white ; their hardnefs fuch as very diSi-*^ 
cultly to be broken by preffure between the fingers. In the 
mouth they immediately fell to a. pulpy powder,, and had no 
tafte. 

A bit expofed on the charcoal to the blow- pipe became 
black, melted like fbme vegetable matters, caught flame, and' 
burnt to a botryoid inflated coal, which foon entirely confumed^ 
away, and vanifhed. 

A piece put into water fell to a powder. The mixture being^. 
boiledy this powder diflblved^ and turned the whole to a jelly. 

Thefc: 



3^4 ^^^ Mac»*s Aceotmt &f 

Thefe properties are txzQXj thofe of comnaon ftarch. 

Agreed entirely with N'^ IV. ia appearaiKe, properties, 
and nature* 

N- VL 

The pieces of this parcel were white, quite opaque, and con* 
fiderably hard. Their tafte and efFefts at the blow-pipe, were 
perfeftly fimilar to thofe of the Hydrabad kind% 

N^VII. 
Much refenabled N® VL only was rather fofter, and fccmei 
to blacken a little when firft heated. With fluxes at the blow^ 
pipe it (hewed the fame effects as all the above% 

Conchjion. 

1. It appears from thefe experiments, that all the parcels, 
except N"* IV. and V. confided of genuine Tabaflieer ; but that 
thofe kinds, immediately taken from the plant, contained a 
certain portion of a vegetable matter, which was wanting ia 
the fpecimens procured from the fliops, and which had pro- 
bably been deprived of this admixture by calcination, of which 
operation a partial blacknefs, obfervable on fome of the pieces 
of N^ III. and VI. are, doubtlefs the traces. This accounts 
alfo for the fuperior hardnefs and diminiflied taftes of thefe 
forts. 

2. The nature of this fubftance is very different from what 
might have been expefkcd in the produft of a vegetable. Its 
indeflrudibiliry by fire ; its total refijdance to acids % its uniting 



fime chtmlcal Experiments en Tabafheer. 385 

bjr FuHqii with alkalies in certain proportions into a white opaque 
fsafs^ in others into a tranfparent permanent glafs ; and its being 
again ieparable from theie compounds, entirely unchanged by 
acids^ &c. feem to afford the ftrongeft reaibns to confider it as 
perfectly identical with common Jiliceous earths 

Yet from pure quartz it may be thought to differ in fbme 
material particulars ; fuch as in its fliiing with calcareous earth, 
in fome of its eSt&s with liquid alkalies, in its tafle, and its 
fpecific gravity. 

But its tafte may arife 'merely from its divided date, for 
chalk and powdery magnefia both have tailes, and taftes which 
are very (imilar to that of pure Tabaiheer ; but when thefe 
earths are tdcen in the denfer ftate of cryftals, they are found 
to be quite infipid; fo Tabaflie'ery when made more folid by 
^xpofure to a pretty flrong heat, is no longer perceived, when 
chewed, to a£l upon the palate, ^ IV. (A). 

And, on accurate comparifon, its effefbs with liquid alka* 
lies have not appeared peculiar ; for though it was found on 
trial, that the powder of common flintSj when boiled in fome 
of the fame liquid cauftic alkali employed at § IX> (A), was 
fcarcely at all afted upon ; and that the very little which was 
diffolved was foon precipitated again, in the form of minute 
Jlocculij.ovi expofing the folution to the air, and was imme- 
diately thrown down on the admixture of an acid ; yet the 
precipitate obtained from liquor Jilicum by marine acid was dif- 
covered, even when dry to didblve readily in this^ alkali, but 
while ftill moift to do fo very copioufly, even without the affift- 
ance of heat ; and fotoe of this folution, thus faturated with 
iiliceous matter by ebullition, being expofed to the air in a 
(hallow glafs, became a jelly by the next day, and the day 
after dried, and cracked, &c. exadly like the mixtures § IX. 

Vol. LXXXL Eee (Dand* 



386 Afr. Macie's Account of 

(D and E). And another portion of this folution mixed with 
marine acid afforded no precipitate, and remained perfcftly un- 
affedled for two days ; but oh the third it was converted into 
a firm jelly like that § IX. (F). 

As gypfum is found to m^Xt per fe at the blow-pipe, though 
refr4'\(3:ory to the ftrongeft heat that can be made in a furnace, 
it was thought thatpoffiblyfiliceous and calcareous earths might 
flux together by this means, though they refift the utmoft 
power of common fires ; but experiment (hewed, that in this 
refpeft quartz did not agree with Tabaflieer. But this differ- 
ence feems much too likely to depend on the admixture of a 
little foreign matter in the latter body, to admit of its being 
made the grounds for confidering it as a new fubftance, ia 
oppofition to fo many more material points in which it agrees 
with filcx. 

Nor can much weight be laid on the inferior fpecific gravity 
of a body fo very porous. The infufibility of the mixture 
§ XIII. (G) depended alfo, probably, either on an inaccuracy 
in the proportions of the earths to each other, or on a deficiency 
of heat. 

3. Of the three bamboos which were hot fplit bcfi^re the 
Royal Society I have opened two. The Tabaflieer found in 
them agreed entirely in its properties with that of N"* I. 
and II. 

It was obferved, that all the Tabaflieer in the fame joint was 
exaftly of the fame appearance. In one joint it was all fimilar 
to the yellowifli fort N® I. In another joint of the fame 
bamboo, it refembled the variety (c) of N"* II. Probably, 
therefore, the parcels from Dr. Russell, containing each feve- 
ral varieties of this fubftance, arofe from the produce of many 
joints having been mixed together. 

4. The 



Jomt chiftucal Experiments . on, Tabaflieer. 3;8 7 

4. The aflies, obtained by burning the bamboo, boiled in 
marine acid, left a very large quantity of a whitifli infoluble 
powder, which, fufed at the blow-pipe with foda, efFervefccd, 
and formed a tranfparent glafs. Only the middle part of the 
joints was burned, the knots were fawed off, left, being po- 
xoufi Tabaflieer might be mechanically lodged in them. How- 
ever, the great quantity of this remaining fubftance fliews it 
to be an effential, conftituent part of the wood. 

The aflies of common charcoal, digefted in marine acid, left 
in the fame manner an infoluble refiduum which fufed with 
foda with effervefcence, and formed glafs ; but the proportion 
of this matter ]to the aflies was greatly lefs than in the foregoing 
cafe. 

5. Since the above experiments were made, a fingular 
circumftance has prefented itfelf. A green bamboo, cut in the 
hot-houfe of Dr. Pitcairn, at Iflington, was judged to con- 
tain Tabaflieer in one of its joints, from a rattling noife dif- 
coverable o\\ fliaking it; but being fplit by Sir Joseph Banks, 
it was found to contain, not ordinary Tabaflieer, but a folid 
pebble, about the (ize of half a pea. 

Externally this pebble was of an irregular rounded form, of 
a dark-brown or black colour. Internally it was reddifli-brown, 
t)f a clofe dull texture, much like fome martial filiceous ftones. 
In one corner there were fliining particles, which appeared to 
be cryftals, but too minute to be diftinguiflied even with the 
microfcope. 

This fubflance was fo hard as to Cut glafs ! 

A fragment of itexpofed to the blow-pipe on the charcoal did 
not grow white, contract in' fize, melt, or undergo any 
change. Put into borax it did not diflblve, but loft its colour, 

£ e e a and 



388 Mr. Macie's Account^ &c^ 

and tinged the flux green. With foda it cfFervefceJ, and 
formed a round bead of opaque black glafs. 

Thefc two beads, digefted in fome perfcftljr pure and white 
marine acid, only partially diflblved, and tinged this menftruum 
of a greenifli yellow colour ; and froni this folution Pruffite 
of tartar, fo pure as pot, under many hours, to produce a blue 
colour with the above pure marine acid, inftantly threw down 
a very copious Prufliaii blue. • 

P. S. In afcertaining the Ipecific gravity of the Hydrabad 
Tabaftieer, § I. (G), great care was taken in both the experi- 
ments that every bit wa& thoroughly penetrated with the water, 
ind tranfparent to its very center, beforp its weight ia the 
water was determined. 




C B^9 3 



XXIIL j1 Second Paper on Hygrometry. 
By J. A* De Luc, Efq. F. R. S. 

Read July 14, I'j^gu 

PART 11. 

IN the firft part of thia Paper * I have treated of the fund^* 
mental principles of hygrometry, and of fome hygrofcopic 
phenomena ; and this will relate to a particular application of 
thofe premifes. 

62. Since the publication of my firft hygrometer, many 
others have been invented, two of which ar« now principally 
in ufe ; the hair hygrometer of M. de Saussure, and my 
bygrometer made of a Jllp of whalebone. If the comparative- 
points of thofe inftruments could be determined in the whole 
extent of their fcales, the only inconvenience of their being^ 
both ufed would be, the neceflity of reducing to one of them, 
the obfervations made with the other; but from 70 to 100 of 
mine, which fpace includes the moft important period of moif- 
turey their correfpondent indications are as different from one 
another, and as variable, as if they were the efFefts of two very 
different caufes. Therefore it is important to decide which of 
them (hould remain our only meafure of moifiure^ till, if pof- 
fible, a better one is found. The following pages,. I hope,, 
will lead to that decifion. 

* See Page u of this Volume* 

a (>^* The 



^9^ Mr. D^ Luc on 

6^ The fundnrnehtal procefs of M. de Saussure, with the 
n^icvv of difcovering the efFefts of moifture on the bair hygro* 
3ncttf\ was this. He repeatedly caufed fucceffive known quan- 
tities of ivater to evaporate into a clofe gfafs veflei, previoully 
reduced to extreme drynefs^ and containhig that hygrometer and a 
manometer \ he obferved the correfpondent changes of thofein- 
ftruments, and, by combining the rcfuUs of his experiments, 
he reduced to regular feries the correfpondent motions of the 
two inftruments by equal quantities of evaporated water. 
Having confined himfelf to that only clafs of experiments, 
•which, from caufes that 1 (hall explain, could not difcoverto 
him the difficulties of his attempt, he thought himfelf war- 
ranted to draw from them the following conclufions. ift. 
That the degrees of moijiure in the inclofed medium^ were nearly 
proportional to the quantities of water evaporated lii the veffel ; 
and that, confequently, the ratio obferved between thcrfc quan- 
tities and the march of his hygrometer^ could be confidered as 
giving immediately the march of the inftrumcnt correfpondent 
to moijiure itfelf; which, according to our common opinion, 
is a certain quantity of aqueous vapours fpread in the medium. 
2dly, That when no more water could evaporate in the veflei, 
the inclofed medium was arrived at extreme moijiure \ and that, 
confequently, the point indicated at that time on his hygro^ 
meter ^ was to be the limit of \lsjcale on that fide. 3dly, That 
having, from thofe experiments, a probable determination of 
the (xpanjions of the hair by fucceflive equal quantities of moif* 
ture^ in beginning from the point were this is null, and ending 
^t its extreme J his inftrument could not differ eflentially from aa 
abfulute hygrometer. 

64. Thefe conclufions were very natural in the ftate of M* 
DE Saussur£*s experiments; but before their publication I had 

gone 



Hygrometry. ^91 

gone ovtr a great field of bygrofcopic phaenomeua, in which? 
the hair^ and a clofe vejjel^ had a (hare ; and thereby, feeing 
the ohjefts in another light than M, de Saussure, I doubted 
of his conclufions, and I procured three of his hygrometers^ \\\ 
order to examine them on fome particular points. It was after 
that immediate verification of my conjedlures concerning his 
inftrument, that I fettled the following conclufions, very dif- 
ferent from thofe above, ift, That moisture, or the quan* 
tity of vapour fpread in the medium itfelf, does not increafe in 
an inclofed fpace in proportion to the quantity of water cva^ 
pcrated in it ; becaufe of an increafing, but undetermined, part 
of that water being depofited on the fides of the yeflel ; and 
that, confequently, Mr. de Saussure's experiments could not 
afford the determination of a real bygrofcopic- fcale. 2dly, That 
the circumftance confidered by him as a fure fign of extreme 
moijlure exifting in the inclofed medium^ namely, the maximum 
of evaporation in the fpace, has only that effed when the tem^ 
perature is very little above 32° ; but that, by fucceffive in- 
ereafes of heat from that point, moijlure recedes farther and: 
farther from its extreme i or from the point where no more 
vapour can be introduced in the medium witiiout an immediate 
precipitation *y though at the fame time, there are fuccefllve in- 
creafes in the quantity of vapour^ and thereby a conftant maxi^ 
mum of evaporation correfpondent with the adlual temperature.. 
3dlyf That, in approaching to extreme moijlure^ the hair hygro- 
meter hccomts Jiationary^ and afterwards a little retrograde, in 
which march the unavoidable irregularities of every bygrofcopic 
fubdance produce frequent anomalies; from which caufe it 
was very difficult for M. de Saussure, confidering the form 
of his experiments, to difcover the bygrofcopic law exprcffed by 
the fccond.conclufion ;. and with the unknown exiftence of that 



39^ ^^* i>B Luc OH 

law^ to fufpie6l the march of his hygrometer: which accidental 

complication I (hall explain hereafter. 

65. When I publiftied thofe refults of my experiments and 
obfervatious, M. D£ Saussure rejected them ; not from having 
made new experiments that had confirmed his opinions ; but 
bfecaufe he conjedlured inverfely, that my theory refulted from a 
fallacious march of my hygrometer: and the well-earned 
reputation of that celebrated philofopher engaged me to 
undertake every experiment that could help me to dete^ on 
which fide was the error. I have related, in the firft part of 
this Paper, feme of thofe experiments; and now, for their 
application, as well as for giving an account of fome others, I 
(hall follow more particularly M. d^ Saussure^s procefs* 

66. In a large glafs vefTcl, containing (as I have mentioned 
above) a manometer and his A^/r-hygrometer, which vcflcl he 
had previoufly reduced to a known fmall diftance from extreme 
drynefs^ M. DE Saussure introduced from time to time a piece 
of wet cloth, which he weighed both before he put it into the 
veflel, and when he took it out. The fucccflive increafes ia 
the quantity of vapour refulting from that procefs were indi- 
cated; on the marr^meier^ by fucceffive increafes in the quantity 
of the inclofed elajiic Jluids^ which caufed the quickfilver to 
afcend more and more in that inftrument; and on the hygro^ 
meier^ by fucceflive expaiifions of the hair. The maximum of 
evaporation was clearly indicated by the manometer ; for, during 
every latting temperature^ the quickfilver, after having afcended 
to a certain .point, remained fixed at that point, notwith* 
ftanding a longer ftay of the wet cloth ; and by repeating that 
operation at ditFerent temperatures^ M. de SAUSi^CRE determined 
the quantities of evaporated water that, in a given fpace, and 
by a given temperature^ produced the maximum o£ evaporation. 

That 



Hygromttry. 393 

That (ingle determination, from its gireat confequences not 
yet generally attended to, would be fufficient to fix the cele- 
brity of its author, as I have already expreffcd many times in 
other works. 

67. But with refpefl: to a different conclufion from the fame 
experiments, no lefs important to natural philofophy, I have 
alfo faid, that M. de Saussure's hygrometer may have mifled 
him. We have feen, that the manometer indicated, by an 
indubitable fymptom, the maximum of evaporation ; for here 
the immediate caufe is clearly known, namely, the quantity of 
elq/lic fluids ; and it is evident, that the quickfilver muft afcend 
in the infirument in proportion to that quantity^ and ftop when 
it Ceafes to increafe. But it is not the fame as to the indica- 
tions of the hygrometer in refpedk of moijlure: M. de Saus- 
SURB found himfelf that they were far from proportional to 
the intenfities of their caufe ; and in the laft ftage of his ex- 
periments, though thefe indications did not vary much by the 
difierent maxima 6i evaporation^ they however varied in the 
fpace of I or 2 degrees. But as thofe fmall differences on the 
point where the hygrometer flopped in different experiments, did 
not follow apparently any law conformable to the temperature^ 
M. DS Saussure confidered them as fmall anomalies^ una- 
voidable in hygrofcopic fubftances, and of little confequence 
on a fcale of 100 degrees ; therefore, laying afide that circum« 
ftance, he could have no doubt, that, in every temperature^ 
the maximum of evaporation in a clofe fpace was fynonymous 
with the maximum of moifture in that fpace ; while, from my 
experiments, thefe two fuppofed identical expreffions may differ 
4, and fometimes f, of the real fcale of moifture^ which is the 
cafe in the temperature of only 75'' or 8o^ 

V0L.LXXXL Fff 68. Let 



294 ^^^ ^^ ^^^ ^^ 

68. Let us now fuppofefor a moment, that the above hygrofco- 
pic law^ and the march that I attribute to the hair hygrometer, 
are real. In that cafe, if, during a conftant maximum oi evapora* 
iion, the temperature varies from 32"" to 80"", moijiiire will dimi- 
nirti \ and even J of the whole ; or, in other words, the ftatc 
of the medium will be diftant by fo much from that in which a 
new introdudlion of vapour would be followed by a precipita* 
iion. But at the fame time, in the whole of that period of 
moijlurcj the hair hygrometer is fuppofed to move only i or 2 
degrees backwards and forwards, with frequent irregularities. 
Therefore, in the hypothefis, fuch a great change of moijiure 
would be hardly fufpe£led from thofe fmall deviations of the 
hair hygrometer, in which at firft nothing appears to be regu- 
lar ; and thereby it is evident, that, by confining himfelf to 
thofe experiments, M. de Saussure could not difcover thofe 
two important laws of bygrology and hygrometry^ of which 
I have here only fuppofed the exiftence. 

' 69. Let us fuppofe agaui, that the hair hygrometer had not 
cxifted before a certain number of other experiments ; and that 
M. DE Saussure, in his attempt to produce an inflrument of 
that kind, had fixed on any of tht Jlips made of ^^r^w vege- 
table or animal fubftances cut acrofs th^ fibres^ of which many 
hygrofcopes had been made before in a coarfer manner ; and 
that, in every other refpeft, he had proceeded as he has done 
with the hair. In that cafe, having placed his hygrometer and 
the manometer in the fame veffel, with a quantity of water 
fufficient for producing the maximum of evaporation in every 
common temperature^ and obferved alfo the points where 
both inftruments flopped in different lading temperatures^ he 
then would have found ; that the hygrometer indicated lefs and 
lefs moijiure^ at the fame time that the manomeUry by afccuding 

more 



Bygrometry. 39 j 

more and more as the evaporation increafed by more beat^ indi- 
cated thatincreafe in the quantity of vapour^ diftinft from the 
expaniions of the Jluids ; and that each of thofe inftruments 
remained alfo fixed in that ftate of oppofite changes, by every 
fufficiently durable change of temperature. The firft obferva* 
tion of that phaenomenon would have furprized him, as it 
did me, and it would have induced him alfo to try fome other 
of thofe Jlips ; and by finding the fame phaenomenon with 
every one of them, he would have been convinced, that it was 
a real faw of moifiure. Laftly, if he had known Mr. James 
Watt's obfervations on the great drynefs of the Jleam of boi/^ 
ing ivater^ as long as it remains in a fpace as warm as the 
water that produces it (a condition always underftood when the 
general laws of evaporation are the objedl of inquiry) ; admit- 
ting with me, as it follows from his own theory, that ixxchjieam 
is no other than the fame kind of vapour thus far mentioned, 
only rendered capable of a greater denjtty by more heat ; he 
would then have feen the importance of that hygrojcopic law 
from its great extent. I have hardly any doubt, that extreme 
drynefs would reign in a clofe place fimilar to Papin's digeflor^ 
if there were a fufficicnt fpace above the water and a red 
heat ; though that fpace would be filled with vapour to the 
maximum. This relates only to the hygrojcopic law here in 
view, on which, in the fuppofed cafe, I do not think we could 
have had any controverfy. 

70. Laftly, let us fuppofe, that in order to try the efFedl of 
moijlure on the fubftance he had firft chofen, or on fome other 
of the fame kind of fubftances, but taken lengthwife^ M. de 
Saussure had happened to try firft one of thofe which, 
ufed in that manner, have a great retrogradation^ as goofe-quill 
and deal I and that, after having' previoufly obferved it in the 

F f f 2 open 



J ^6 Mr. DE Luc on 

open air, he had inclofed it in the fnoifi vej/il^ at a time when 
the place where it ftood before had the degree of moijiure cor- 
refponding with the Jiationary ftate of that hygrofcofe^ ho 
would then have obferved a phaenomenon as little expefted as 
the former : for after that inftrument had been inclofed in the 
motjl vejfely it would have moved, by that increafe of moifture^ 
in the fame direAion as it had done in the open dry air when there 
was on the contrary an increafe of drynefs, Surprifed no doubt 
at that phaenomenon^ M. db Saussurb would have fubmitted 
his new inftrument to more experiments ; he would alfo have 
tried other threads^ in which he would have found the fame fort 
of marc&f only at various degrees; and if, in thecourfeof thofe 
trials, he had fubmitted the hair to the fame experiments, the 
fmallnefs of its motions backwards and forwards, and their irre- 
gularities, would not have prevented him from difcovering in it 
the fame fort of marcA as he had then been ufed to fee in other 
threads \ and thereby, he would have abandoned the whole 
tribe of threads as unfit for the hygrometer. 

71. The whole of that fuppofed courfe of experiments with 
Jlips and threads^ is that which I have followed from the time I 

had abandoned the conftruflion of my firft hygrometer ; which I 
did efpecially with the view of being able to try many fubftanccs. 
Therefore my theory was formed in confequence of the two 
above conclufions, which appear to me immediate, and fuchas 
M, DE Saussure could not have drawn differently, if he had 
followed the fame necefTary fleps : aijd now I will prove, more- 
over, that if it had not been for accidental circumflances in his 
own proccfs, the hair alone would have engaged him by degrees 
to undertake the fame experiments. 

72, M. DE Saussure*s firfl hygrometers^ having thAv index zt 
the top of the frame, could be plunged into water ; and he 

tried 



Hygrometry. ^gy 

tried that method for fixiDg their point of extreme mot/lute^ as I 
had done for my firft hygrometers. But in thofe trials he obferved, 
that while his inftruments flood in water ^ their indications re- 
mained undetermined within a fpace of four or five degrees ; and 
attributing that irregularity to zfriSlion of xh^hair with water ^ 
he thought it necefTary to change my method, to that of placing 
the inftrument in a moijl mediumj which he produced by means 
of a glafs jar, wet on the infide, and inverted over water. In 
this method, the fituation of the index became indifferent; 
and, for fome particular reaibn, he placed it at the bottom of 
his new hygrometers^ which then could not be plunged into 
water. This laft circumftance was merely accidental ; how- 
ever, we (hall fee how much it has influenced his opinions 
in refpeifl of extreme moifture. 

73. In the firft account of his experiments, M, de Saus- 
suRE did not enter into thofe particulars ; but they are in hi& 
anfwer to me : and when 1 there faw, that he gave as a reafoik 
for having abandoned the immerfion in water ^ that a /Irong ad^ 
h^on of the hair to that liquid impeded the freenefs of Its 
motions, I found it more natural to ailign to the inflrument 
itfelf the unfleadinefs of its index which he attributed to that 
caufe. Indeed, in thofe firfl hygrometers^ one end of the axis 
pafTcd through a hole for the purpofe of carrying the index out- 
wards, which was a caufe of much fridlion : that axis befides 
was loaded with the weight of pretty large pincers, holding 
the hair^ and tliat weight was counterpoifed on the other fide. 
Laftly, the connexion of the hair with the index was produced 
by zfilver lamina^ which, though very thin, oppofed fome re^ 
fiftance in bending round thtfixis. Thofe are dcfe£ls that M. 
DB Saussure corrected afterwards ; but they exifted in the 
inflruments which he plunged into water^ and a weight .of 

5 ^«^y 



29^ J^^^ DE Luc en 

only 3 grains was not fufficierit tokeep their index fteady, cither 

in water or any where ; and this he obferved himfelf. 

74. Notwithftanding that natural explanation of the unftea- 
dinefs of M. r>E Saussure*s firft hygrometer when in water ^ I 
thought it neceffary to try, in the fame circumftance, fome 
well-con ft ru6ted hair hygrometer ; therefore I made two, fimi- 
lar to the laft of M, de Saussure^s in every refpeft, except 
that of having their index at the top ; and for the conneftioii 
of the hair with the axis^ I ufed a kind of pincers^ not above 
half a grain in weight, with a hair- like bit of bemp^ which I 
know does not alter in any fenfible manner the march of the 
inftrument. Now, thefe hair hygrometers, with their weight 
of only 3 grains^ being put into water ^ follow in it their own 
laws, arrive and remain fxed at their once fettled point, as 
well as any of my other hygrometers. This M. de Saus- 
suRE would have alfo found, if in the improvement of his 
inftrument the axis had remained at the top. 

75. Before I explain the influence which that accidental cir^ 
cumftance of the place of his index hzs had on his opinions with 
refpcft to extreme tnoijlure^ I muft mention another of the 
fame kind which has contributed to the fame efFeil. It is evi- 
dent, both from theory and from M.,de Saussure*s own expe- 
riments lelated above (§ 66,), that a fufficient quantity of wa- 
ter in any part of a clofe veflel is the only rcquifite for pro- 
ducing in it the maximum of evaporation ; but, with a view of 
accelerating that efFedt for the common purpofe of fixing the 
point of extreme moifture on his hygrometer^ he prefcribes 
wetting the infide of the veflel, befides inverting it over 
water. He did not (and indeed he could not) forefee the 
confequence of that alteration in his firft procefs; but in 
fad it was fuch as to prevent him from difcovcring, even with 

time. 



Hygrometry. ^g^ 

time, in thofc operations, what he would have fcen immediately 
if his laft hygrometers could have been plunged into water. 

76. After the improvement of his hygrometers, their index 
was no more fubjedl to that unfteadlaefs obferved in the firft ; 
confequeutly they remained Jixed under the moifi veffel\ but 
they did not^ at the fame point every time ; and it happened 
accidentally^ from caufes of irregularity in the vejjel itfelf, that 
in fome of the cafes, when the hair was the longejf^ a precipi-^ 
tation of water happened (by fome partial cooling) on fome 
part of that veffel; and he took that appearance for a fure (iga 
that there was a fuperjiuous quantity of water in the inclofed 
air. From that accidental connexion of circumftances he con- 
cluded, that his hygrometer indicated two different ftates of the 
medium in refpeft of extreme moijiure ; one, correfpondent to 
about 98 on that inftrument, vi^hich he confidered as real ex^ 
treme moifture, or that ftate of the medium in which no more 
v^/(?«r could be introduced into it without 2l precipitation ; the 
other, when fuch, a precipitation took place, which he made 
correfpondent to 100, or to the greateft length of the hair^ 
Prepoflefled afterwards with that opinion, when I publiflied my 
comparative experiments of his hygrometer and mine, in which, 
the latter flood fometimes at 80 when the former was at 98^ 
he concluded from that circumftance, that while his hygrome* 
ter moved only 2 degrees by tjie utmoft efFe£l of a fuper^ 
Jaturation of the medium^ mine had 20 of thofe injignijicant 
degrees. In this centers the whole of our'difagreement, and I 
am now going to trace its caufe in the cccid^^tid circumftances- 
above dcfcribed, 

- 77. When I plunge my hair hygrometers into water ^ where,, 
as I have faid, they come to ^ fixed ^6\\\Xj that point does not 
indicate the ^T^^/i^/? length of the /Wr ; for, on the contrary,. 

that 



40^ Mr. o£ ttvc $n 

that thread is ihtnjhqrter than it is moft times under the moljt 
veffeh This M, de Saussurb would have feen, if he had not 
been prevented, by the fituation of the index in his improved 
hygrometer y from trying again the efFc6: of water on the hair\ 
and that phaenomenon alone would furcly have given a different 
courfe to his ideas ; efpecially he would not have fuppofed, that 
the hair lengthens z degrees more, by zfuper^faturation of the me* 
dsum, or by the immediate contaft of concrete water. 

yS. If, alfo, when he fettled the manner of determining 
the point of extreme mojfiure on his hygrometers^ M. de Saus- 
surb had retained the fimplicity of the procefs he had ufed for 
his fundamental experiments, in which a piece of wet cloth 
had been fufiicient for producing xh^ maximum of evaporation 
in his large veiTel ; and, in confequence, had contented himfelf 
with inverting his glafs jar over water^ without wetting it 
on the infide, he would have avoided a great caufe of decep- 
tion which i am going to explain. In my firft experiments on 
the comparative marches of our hygrometers, in which I fol- 
lowed M. DE Saussure*s prefcription for the moijl veffel^ I 
found fome anomalies which puzzled me. M. de Saussurs 
himfelf took notice of them in the account I gave of thofe 
experiments, and attributed them to my inftrument. I did not 
agree with him in that refpe£t ; but it was long before I could 
difcover the real cau£e of thofc anomalies. The firft flep 
towards that difcovery, was the reflefting on the ufclefliiefs of 
nvetting the veffel on the inlide, for the only purpofe of pro- 
ducing in it rhe maximum of evaporation. That confideration 
engaged me to undertake a new courfe of the fame experi- 
ments, with a glafs jar merely inverted over water ; and by 
that means, the greateft part of the real anomalies being re- 
moved, I obferved clearly in the march of the hair^ the 

combined 



Uygnmetry. 401 

combined effeSs of its own property, and of the hygrofcoplc 
law refpcfting evaporation which was known to me from other 
phsenomena. 

79. As for the caufc of thofc anomalies which had been 
removed by the change of the proccfs, the following phenome- 
non led me to difcover it, I obferved frequently, at times when 

. my hygrometer y placed under the jar, flood at a confiderable dif« 
tance from its point of extreme moijiure^ that a very fmall dimi- 
nution of heat was fuiiicient to caufe, on the lower part of the 
vefiel^ the formation of a tarnijhed rim, extending one or two 
inches above the furface of the water^ with a thin vauifliing 
edge. Having refleded on that phaenomenon, from the me- 
chanifm I aflign to the operation oi fire in the very zQi of 
evaporation I concluded, that in fuch a Jlagnant air every eva-> 
porating furface had an atmofpbere of extreme moifiure^ which 
extended as indicated by the tarnijhed rim ; and that it was 
only beyond that limit that reigned the other law^ of a de* 
creafing moijiure^ correfpondent to the increaiing maxima of 
evaporation by an increafing heat. That new law of evapora-^ 
iion ofiered evidently an adequate caufe for explaining the ano- 
malies obferved in the wet veflel ; for glafs retains concrete 
water very imperfeftly, and it runs down very foon from 
many of the places which had retained it. Confequently^ 
under fuch a partially wet vel!el, and differently fo at different 
times, the inftruments mnfl be variouily affeded by fcattered 
atmojpheres of extreme moifiure^ 

80. However, before I could truft that explanation, I 
wanted to fubmit it to fome diredl experiment ; and I fuc* 
ceeded by a means which at the fame time realized what M. 
P£ Saussurs thought he had obtained, namely, to produce ex^ 
treme moijiure in a cloie fpace, during any common temperature^ 

Vol. LXXXI. Ggg without 



4ot Mr. DK Luc wi 

without any precipitation of water &om the medium. This I 
have produced by means of a wire cage, 4 inches in diameter, 
covered with cotton cloth, having at the top a referooir^ by 
which the cloth is kept thoroughly wet for a long time ; which 
cage beiides is inclofed in the glafs jar inverted over water. In 
that apparatus, though in fummer-time, every hygrometer^ 
either thread or Jlipj moves and fixes itfelf, not io fpeedily, but 
elfe exa£lly as if it was plunged into water^ without any Jkper^ 
Jaturation 'of the inclofed medium^ or precipitation of water on 
the bygrojcopic fubftance* 

^81. We may fee now that the idea of two forts of extreme 
moijlure is without any foundation. In order to enforce the 
iieoefiity of taking the point of extreme mejfiure in the air 
brought to that ilate, and not in water ^.M. de Saussxjre fayc^ 
** That the hygrometer is not to meafure the moi/lure of watir^ 
^^ but that of the tf/r.** This at firil appears plausible; how* 
ever, in reality^ moijlure is no more to be confidered in water 
itfelf, than heat in the Huid called ^r^. fFater is the cauie of 
moi/lure J t:^ fire is the caufe of beat\ but thofe effeSs are not 
produced on their caufes ; it is m other fubftances. Therefore, 
if fome bygrofcopic fubftances are placed in a medium which has 
attained extreme moi/lure^ and, in proportion as they take 
water from it, the io& of that water be cdnftantly repaired 
by a new evaporatien^ they will receive by degrees in fuch a 
medium^ without any precipitation^ as misch water as if tbey 
were plunged in water itfelf; for the limit is their capacity^ 
which I have explained in § 19. This is the fame theory that 
1 had exprefied in my firft Paper on Hygrjometry ; and it is com" 
plctdy confirmed by the above experiment, with the difcoveiy 
of this ntvr hygro/eopic law^ " That in z Jlagnant air^ every 
< ^' evaporating furface has an atmofpber€ of extreme mo^e^ 

*^whfich 



IfygrH>metry^ 403 

^ which extends In a fpace of few inches, dtmini(hes rapidly^ 
** and does not interfere beyond that limit with the other /aws 
« of mifturer 

82. I fhall now explain, by an example, what is the funda- 
mental deviation of an hair hygrometer ^ introducing in it, for 
a moment, thofe two lingular points 98 and 100, which, in 
M* DE Saussurb's experiments, were a very natural caufe of 
miflake. A hair hygrometer and mine, being in a clofe vef- 
&1, at a time when the temperature^ fenfibly conftant, (hall be 
but little above 32 ; if moijiure is firft introduced into that veflel, 
lb as to bring the hair hygrometer, by a very flow dired motion, 
lo 98, my hygrometer will flop between 70 and 75 ; and both 
inftruments will h^ fixed, if moijiure and heat remain the fame. 
Let moijiure then be made to increafe very flowly, till the hair 
hygrometer has attained its point 100 ; mine will have arrived 
at 80 ; and they again will remain at thofe points as long as, 
with the feme temperature^ the fame quantity of vapour (hall 
remain in the veflel. Laftly, let a fufficient or fuperfluous 
quantity of water be introduced into the vcflTel, the hair hy- 
grometer will retrograde to 98, and mine proceed to 100, at 
which points they will flop, whatever be the quantity of wa^ 
ter ; and they will remain fixed, as long as the heat fhall not 
increafe. This explains the riddle of the (ingular point 98, or 
of a certain pointy various in different hair hygrometers, various 
even, at different times, in the fame individual, at which that 
inftrument (buds with very different degrees of m^^i/r^; confe- 
quently, its little motions round that point may create great 
deception, efpccially from the nature of orgam%ed fubftances, 
en which now I (hall add a few words. 

83. The above is the fundamental march of the Au/r hygro- 
meter, fuch as it is on the whole, and as it would be con- 

Ggg2 fiantly, 



404 Mr. DE Luc OH 

ftantly, if no other caufe interfered ; but it is fubjcd W dif- 
turbing anomaliesj which become worthy of attention within* 
that fmall critical fpace which I have defcribed. The texturt 
of organized hygrofcopic fubftances occafious z friction between 
their parts, when, by the changes of tnoi/iure and heat com- 
bined with their elajlicity^ they undergo changes in their refpec- 
tive pofitions ; whereby they hardly can completely return to 
the very fame arrangement, though with the fame external 
circumftancfis ; even at extreme moifiure^ when, there being 
lefs friSlion between their particles, the greatefl part of the 
didurbances produced in their former motions are reftored. To 
that general caufe of irregularity is added a particular caufe, 
when thofe fubftances are in the ftate of hygrometers ; this is 
the influence of two oppofite forces a£Hng conftantly on them ; 
one, the tendency of their component parts to remain united ; 
the other, a weight or J^ring wliich tends to feparate them.. 
Certain accidental arrangements of their component parts give 
them mere power to reiifl the adion which tends to feparate 
them; and thofe arrangements are very changeable, by the 
alternate introduction and expulfion of moifiure^ by a long flay 
within a fmall compafs of variations, and by nK)re or lefs 
heat. This is a large field of fads and fpeculations, not un*' 
interefling in itfelf, but on which I mufl not dwell : what I 
have faid of thofe caufes is fufiicient to account for the anoma* 
lies to which, more or lefs, every hygrometer is fubjeft. But 
whereas in the Jlips^ thofe anomalies create only fome irregulari- 
ties in the obfervations, without any deceiving confequence in 
refpe(ft of the laws of moifiure^ they may deceive when they hap- 
pen to interfere in the critical part of the march of fome threads ; 
for inflance, if, by a certain accidental arrangement of the con- 
flituent parts in a pp of whalebone^ there happens to be fome 
a tenths 



Hygromeiry. 405 

Unth of a degree difFcrcnce, from one experiment to a^iother, 
ou its point oi extreme moljture^ that anomaly cannot be of anjr 
confequence on the determination of what mufA be confidered aS: 
that ftate in the medium; but if it happens to xh^bair^ whieh> 
in approaching extreme motfture^ has but very fmall motions^ 
it may rever(JB thofe which it had had naturally (as I have ob* 
ferved it fbmetimes) and beconae a caufe of deception. 

84^ 1 have now explained, how mere accidental circum- 
fiances have been the caufe of a difK^rence in the ideas that M.. 
DB Saussure and I had formed on what is' to be under- 
flood by extreme moifture in every cafe ; and I am going ta 
illuftrate the whole of that fubjeft by a Angular faft. Aii» 
hygrometer made with a box thready or a thin fafcicle of 
the fibres of that wood, being placed in open air, next to- a 
hair hygrometert or to moft of the other inft rumen ts of thaU 
jTort, moves in a contrary way from them ; but we may lay 
afide that circun>ftance, by fuppofing, that the numbers^ marked 
on the dial of the firft, are increaiing in the oppofite direflionb 
from thofe of the other inftruments. Let u»then fuppofe, that 
ibme experimental philofopher had chofen the box thread fof 
his hygrometer ; with him I (houM have fallen into no contro^ 
verfy on the point of extreme moifture ; for, either under the 
moijl vejfelf or in any othej cafe approaching extreme moifturey 
his hygrometer would have moved like mine. But the bo^ 
thready at approaching extreme drynefs^ firft relents much its 
pace, then becomes ftationary^ and afterwards retrograde ; by 
which property, with the concourfe of fome accidental circum?- 
ftances as have happened in M. de Saussure*s experiments,, 
the very fame queftions that I have examined with fo muclv 
labour in refpedl of extreme moijlure^ only becaufe of the hair 
hygrometer, would have been tranfported to the point of exr 

treme 



4q€ Mr. Ds Lue on 

ireme dryneji% which^ however, till now, has created no 

<doubt. 

85. That Angular /ArM^illuftrates alio another point, clofely 
ccon nested with the retrogradation of its tribe, but not to be 
confounded with it; I mean the recoil. The common caufeof 
both phaenomena is, two oppofite effeSis produced by changes 
of moifiurej on the length of threads. The retrogradation in 
the marcbj comparatively to that of moijiurey is produced by 
one of the effeSis^ which before was furpafl'ed by the other, 
becoming predominant ; and the recoil^ or a returning back a 
}>art of a firft ftride when moijiure changes fuddenly, is pro- 
duced, by one of the effeHs^ that on th^ fibres themfelves, being 
^exioxmtAfooner than that on the fort of reticle formed by the 
fibres. Now, the box thread having its retrf)gradation at ap- 
proaching extreme drynefs^ there alfo the recoil becomes fenfi- 
ble : it appears in the firft modifications of that thread when 
placed in my dry vejfel^ by motions backwards and forwards, 
as it happens to fome other threads^ when taken out of water^ 
or expofed to any other ftidden change of mot/lure. The box 
thread having a flow motion, no recoil is clearly diftingui(hable 
in its common march ; whereas the hair and the qutll-tbread^ 
which, in appearance, are very quick, have generally a very 
difturbed motion when moifiurt changes fuddenly. \ have fecn 
them, when in a free air, and happening to be in their /tf- 
tionary ftate, moving quickly one way in a fpace of i or 2 de- 
grees, and then recoiling flower, fometimes to the fame point 
where they were before, while my hygrometer underwent a fteady 
change, which was in the firft direftion of theirs. This phae- 
nomenon, of a complete recoil in the fiationary fhtc of quick 
threads J is fimilar to the recoil of the index in thofe glafs frames 
chat I have defcribed in § 59. of this Paper, which have a 

coni'^ 






Hygrometry. 407 

eompenfation for the changes of beat by a thin brafs lamina r 
this being fooner affeded than the glafs rods^ by fudden changes- 
of beat^ the index moves firft one way; then it recoils com- 
pletely, by the change being operated later in the glafs rods. 

86# The experiments briefly related in this Paper will, I 
hope, be fufCcient to anfwer the following queftion, whicb 
has been made to me by fome obfervers of the two principal 
hygrometers here compared : *• Why does the hair hygrometer^ 

when expofed to the open air in day time, come fo often? 

near its point of extreme mojfture^ while the whalibone hygro- 
** meter almoft never comes within 30 degrees diftance of that 
•• point in fummer, and very feldom within 20 in winter, even) 
^ in rainy weather (if prcferved from rain) ?*• The anfwer^ 
according to the refults of thefe experiments, is this : " The 
•* general march of the hair hygrometer is much decreajing^ , 
** comparatively to equal increaies of moifiure ; that march for- 
** wards, cikis in zftalionary ftate, and is followed by a fmal£ 
** retrogradation I while the whalebone hygrometer has con- 
^^ AzntXyzmarchj \f not proportionalj at leaft conftantly ^{#7y//iir 
** to that of moifiure itfelf." 

87. There remains an objeft of inquiry, which is, a deters 
mination of thofe ratios here generally cxpreffed. I have ex* 
plained, in the firft part of this Paper, the difficulties of that 
objeft, and what help may be found in comparing the marches 
of hygrometers with the acquifitions of .weight of their fub- 
ftances, of which procefs I gave fome examples ; and here I 
ftiall relate fimilar experiments on hair^ whalebone^ box^ and 
aloes^pitta. But as I have already defcribed the whole procefs,, 
and the manner of calculation of that clafs of experiments, I 
fliall only give here the refults of thefe laft* 

88. I 



4q8 Mr. Dfi Lvc M 

88. I mufty however, firft explain another redu^kn that I 
have added to the former. la the firft tablb which I have 
given of thofe experloieutfi, I followed the immediate divifion. 
of my i^iftruments, in which o correfpouds to extremt drynefs^ 
and 100 to extreme moljiure. But firft, under that form, the 
point called loo by M. J>s Saussurb would not appear in its 
true light, as it means the greateft length of the hair ; while 
the point lOO of my fcale deiigns the flate of that thread m 
water J where it has a littie retrogradation. Under that form 
ilfo moft part of the terms in the obfervation on the box thread 
would be negative^ fince it moves very long in a contrary direc«> 
(ion to the other hygroicopes. For thefe reafons, inftead of 
calling o the point of extreme drynefs^ ai^d that of extreme moif- 
ture lOO, I have, in the following tables, api^ied the firft of 
thofe denominations to the Jmalleft length of eadi fubftance, 
and the laft to their greateft length. That redu&ion produces 
|io difference in the proportions between the terms^ and none in 
the /^rmx tbemfelves in refped tojlipsi as in thefei the greateji 
length is always obferved by extreme moijiure^ and the fmalleji 
by extreme drynefs. 



II. TiVBLK 



Hygrometry. 



409 



II. Table of comparative changes in the weight and in the 

length of the fame fubftances^ by the fame increafes of moif- 

ture, correfpondent to the march of the flip of whalebone 
from ^tof^of its degrees. 



Bxtr. dryntfs 



WHALS 


BONE. 


HAItt. 


ALOES-PITTA. 


iMrwtoor 

tbe weight 
Snfluvingfc 


MafchW 

tbeflipw 


UtCXttutt of 

the weight 
iaaaii6or 
hair. 


March oT 
the hair. 


Increafet of 
the weight 
ina maCsof 

pitta. 


March 

of the 

thread 

of pitta. 


0.0 





0.0 


ao 


0.0 


0.0 


6.0 


5 


4.8 


>5-7 


6.0 


20.6 


1 1.8 


10 


8.8 


29.0 


ik8 


351 


»7.3 


»S 


«»-5 


40.0 


»7-3 


S1.6 


22.2 


20 


«S-9 


50.4 


22.2 


57.6 


t6.8 


as 


19. 1 


59-7 


i26.8 


75-6 


3i.a 


30 


22.3 


67.S 


31.1 


71.9 


35.!» 


35 


26.6 


74.4 


3SA 


76.3 


39-7 


40 


39.0 


79-3 


39-7 


83.0 


44.0 


45 


32.0 


«3.3 


44.0 


66.6 


48.1 


50 


3S.O 


88.0 


48.1 


93-6 


5a.i 


5S 


38.2 


90.0 


54.1 


96.S 


57' » 


60 


43.3 


92.8 


57. » 


94-7 


61.7 


6S 


49-8 


.94' « 


61.7 


98.2 


66.3 


70 


55.3 


95 4 


66.3 


100.0 


71.9 


75 


61.9 


97.0 


71.9 


99.2 


77.6 


80 


68.7 


lOO.O 


77.6 


98.2 


♦ 83.2 


«S 


• 76.0 


99.5 


• 83.2 


968 


• 88 8 


90 


• 84.0 


99.2 


* 88.8 


94.1 


• 94.4 


95 


♦ 92.0 


98.6 


* 94^ 


91.9 


•lOO.O ' 


too 


♦lOOiO 


97-7 


•100.0 


88.3 



la watir 

89. In the above, and in the following experiments, the 
operation of fucceflively introducing moijiure into the veflel was 
flopped, when iht flip of whalebone was at 80, as beyond that 
term the fmalleft difference in the /^/?//^rj/»r^J>etweenthe parts 
of the apparatus creates great anomalies ; therefore the fol- 

Vol. LXXXI. H h h lowing 



j^to Mr. DB Lvc on 

lowing terms in the three columns of weights, which arc 
marked with an *, have only been added (as I have explained 
for the former Tab/e) with the view of having a common mih 
dutum between the changes of weight and the marches of the 
other inftruments. But the obferved terms remain in their 
original proportions^ and from thefe we may fee, that the march 
of ihtjlip of whalebone does not differ much from the fuccef- 
five increafe of weight in its own fubftance ; and that when 
taken out of the apparatus, and immediately plunged into 
water^ it proceeds hi the fame diredion as before, till it has 
attained its fixed point, while the hair takes, comparatively 
with the increafe of weight of its own fubftance, great flrides 
in the beginning of its marchj and very fmall fleps in the latter 
part of it, before lOo; and then retrogrades a little, when 
taken out of the apparatus, and plunged into water. We fee 
befides in that table, that the thread of aloes-pitta^ which at 
firft takps ftill greater ftrides than the hair^ has, after a longer 
Jiationary or undetermined ftate, a determined beginning of 
retrogradation at the fame time that its own fnbflance conti- 
nues to acquire weight in the apparatus, and continues that 
retrograde march when, being taken out of the veflel, it is 
plunged into water. 

90. The following table will farther illuftrate thefe cha- 
radleriftic differences oi Jlips and threads^ the afeertaining of 
which was fo effential to hygrometry. 



III. Table 



Hygrmetry* 



41* 



IIL Tablb af txperimnts on the comparative ehsnges m the 
weight and the length of the fame fuhftance by increafe of 
moifture. 



Bxtr. iryiufi 







BOX. 




Slip of 


March of 


Increafet of 


March of 


whalebone. 


the flip. 


the weight 
in fharingt. 


the thread. 


ifi 


0.0 


0.0 


72.8 


S 


45 


7-3 


87.2 


to 


9-5 


12.8 


93a 


M 


14.5 


17.8 


97.8 


lO 


ao.d 


22.6 


lOO.O 


25 


»5'7 


«7-3 


959 


30 


^'S 


3J.8 


94.7 


3S 


38.0 


38.5 


88.6 


40 


45.5 


44-5 


79-9 


45 


S^'S 


49-7 


70.3 


SO 


. 56.5 


54.8 


63.9 


55 


61.2 


59.1 


57 3 


60 


65-7 . 


63.1 


51^ 


65 


69.7 


66.4 


47-5 


70 


73-7 


69.6 


40.9 


75 


77-7 


76.6 


5»-4 


80 


81.5 


80.0 


a 1.7 


85 


85.9 


• 85.0 


16.0 


90 


90-5 


• 90.0 


10.4 


95 


95.5 


* 95-0 


5-« 


100 


lOO.O 


* 1 00.6 


0.0 



Itiiyatir 

We fee in this table the Jlip of box following^ in its in« 
creafes of lengthy the increafe of weight in tht Jhavings of the 
fame woodj nearly in the fame manner as the JUps of whale^ 
hone J quill J and deal^ follow thofe of their own (havings; 
while the thread of box^ after having gained fome length by 

H h h a decreafing 



41 A Mr.tfthvcon 

decreafing fteps^ begins foon tojborten^ at the fame time that itff 
fubftance continues to imbibe water ; being thus the Jborttfl^ 
when it cannot receive any more v>aUr in its pores. That excefs 
of the bygrofcopic phaenomenon of threads cannot but throw a 
full light on the nature of thofe bygrofcopes. 

91. I am now going to aflemble, in two TABLSSt thecoma 
parative marches of all the threads^ and of all the Jlips^ which 
I have hitherto fubmitted to that regular courie of experi- 
ments^ laying afide many more of each clafs, i^t marches oi 
which I only know from common obfervations. The next 
T ABLB (hall contain the experiments on threads ; in the num** 
ber of which are two thin natural bodies, which in that refped 
are (imilar to the hair ; one, an animal fubftance» is a very 
thiti porcupine qmlli the other^ a vegetable, is a thin ilem of 
grametiM 



Tablb 



Hygromfr^ 4»f 









• ■ r^ ••••••• 'v^ J** • • • • •• i^ —• B s 

MO\oOO(/iWtOUt06bo900gd(#»o^OoQF|. Jii 

1 W ^ 

^OOVMMMM0000.|k<l^4i.M00M00ae>»«OOO*s-<» ^ 






C*u»bool>ovio<5^o»«^uii>ooJjvAvb-i»o^b ?' SI'S* 

• • • • •^ • •••••• » • • • •_ "^ • « • B a9 Jr^ 






po M ^ ON OOVO p OO-^ ONUJ ONtK» ON«Cn'^7*taOp55' 3 *^ 






mSJaJSooO Ooo^4nSa*$>55uj c»ooo>^ PS; 8 S^P 

Ot i^ \»;^ U b b U h C^ b b i. b b 4^ o ^ bsb o f-f ^ r> 

5 o5^5NO»-^o^SooooS«)u;TJ^S^5^^obc^p i qo K 

O^OUtOOONOO»»ft»OOOOONMUiNOONH^OOO g 9-C 

^ * * §^ 3 

M M iaU»<^^<A(A ON^^*^ OOnOvO SvOnO OO^t ^ ^ ^^ 

OM<».b<^-|k^«'>40M«M>oo>'>4«oo-eoi»<^-oo <^ &^, 

ViOWiOViO(#iOWiOW«0(aO(/%QW«0«a08'; § 



92. There 



92. There the porcupine quill (hews no retrograJationi how- 
vcvcr, confiftent with its tribe, it had fome in other experi- 
ments. Its laft fteps have the unfteadinefs of the Jiationary 
ftate, and thereby are fubjeft to anomalies. From the fame 
caufe, none of the other threads have exaftly the fame fteps in 
any two experiments, though on the whole their march 
remains effcntially the fame. The march here given of the 
hair hygrometer comparatively with mine, is the mean refult 
of three experiments, with three different fets of inftruments; 
one of the hair hygrometers that I have employed was fent 
to me by Mr. Paul, of Geneva, and its point of extreme 
moifture was determined in a fog. The fmall and change- 
able retrogradaiion of the thread of whalebone and of hair 
might have been overlooked, were it not for other threads ia 
which the retrogradation begins before that period where the 
ftate of moifture is difficult to afcertain ; but from thefe tireaJi, 
that phaejiomenon is placed in a clear light, which is refleded 
on the others. I have marked with an * the greateft elonga^ 
tion of each of them, and with a f a point near which their 
elongation begins, and to which they return at laft. Thefe figns 
will guide the eye in the above table* whkh (hewft clearlyf 
that no thread czn be trufted to for the hygrometer. 



Table 



Hygrometijm 



f^S 



M 

D 
























g' 




H 
























• 

5- 




























"§ 




t* 


^ 
























i 




v: 


11 


00 


00 ^ 


v» 


ON 


ON trt Ca #► 4i. 


U) 


Od » 


10 


*•* 


ii4 






p ? 


1 ?• 


oo 

• 


5* ^ 

00 00 


• 

Id 


• 


•-I ON W ^ M 
• • • • • 

NO NO 4^ 4^ NO 


00 ud 00 00 

CM Cjd (A NO 


NO 
• 
10 


4^ 


^ 4- 
•-» •« 



b 


H 


Nt 


























•fl 


i 8 


8? 


oo 


00^ 


^* 


Ov 


ON (A Va ^ ^ 


4k 


'S.^ 


IA 


M 


¥* 






•8 1 


1? 


OOO^ 00 


US 


oo 

• 


4^ NO 4^ NO C^ 


M 


iA» 


^1 


10 


?<»-^ 







0+: 


NO 


NO NO 


iA 


^ 


4^ ^ 00 00 4h. 


4^ 


■t' 


4*' 


b 


b 


00 09 


b 


2-2 


34, 


8« 


^ 


^g* 




o* 


i/« iA Wi 


t 


Sf'S 


Ca 


10 




M 
(A 


CA 





II- 




























? "^ 


95-3 

lOO.O 




00 oo 


• 


^4 


ON ON OiA (A 
NO iA *^ ON 1-4 
• • • • • 

^ -^ *» iA -^ 


(A 


00 M 

b (n 


(A 


84: 
b(;% 


^ 4^ 

wi i;* 



b 


5* 


•§■3 
^3 


^4 




























s r 


Q NO 
O ON 

b 6 


NO 


00 00 


VJ 


•^ 


ON 0»iA iA ^ 


> 


CO iAd 


»» 


Id 


M 


M 




« 


*• Cft 


b 




NO 

b 


Cn 


so 4- NO 4^ NO 

«^ NO NO ON 10 


•s4 




• 


• 
NO 


(A 




P 






1^ 


Q O 
O Ov 

b b 


>o 


00 00 


00 


^J 


•^ On ONi/i i/k 


^ 


4^ to 


U» 


Id 


M 


M 




>4» 


b 


00 iA 


p 


• 


la 00 (M OOOd 
• • • • • 

IN i/l iA <A 




« iA 

NO 4^ 





NO 


00 


10 0^ 



b 


N' 
























- 








8^ 


vO 


NO NO 


00 


00^>» ^ •^ O* O^ Cn 


^ ^ 


CO 


iM 


Id 


N4 




-1 




*» p 




Id 

NO 


%o O^ IN ^*J >d 

• . • • • • 
M M ON** 4»^ 


QN ^ ^^ 

Ua C» ON 


• • 
ONiA 


ON 


?^ 00 

b»i^ 



b 


»4 


























«. y 


» §. 


S'g. 


VO 


so >0 


00 


90 


00^ ^ "Nj ON 


0^ iA i/t 


4^ 


U9 


Od 


>d M 




l| 


c; 


p^*- r 


9«» 


i^ 


M NO ON l» NO 
• • • • • 


• 


00 M 


Cx 


00 


• 


•-• 1-4 

• • 





^ c? 


b b" 


*> 


00 »» 


^ 


NO 


4. 4^ 41. 00 


OOCfd NO 


i' 


iA 


iA 


iA 


b 


5* 


il 


M 


























^. 


g:? 


Si; 

• • 


NO 


vO ^0 


NO 


00 


00 00 -^ vj -N^ 


Ov 


ON iA 


4^ 


CO 


10 


^4 




s- s 


"giS: 


pv 


4^ *d 


p 


£» 


OS -^ NO -^ M 
• 5^ • • • 


00 

• 


t» i" 


ON^ 

• 


• 


00 NO 





li 


O « 


M 


b b 


l» 


•^ 


4^ W ^ Od 


**J 


M ca 


iA 





iA 


Cn Cn 


b 


T 


H 


8S 


NO 


NO NO 


NO 


^o 


NO 00 00 00 ^ 


^4 


^ ^<A 


% 


(«d 


^ M 




If 


^ 


^J 


^ C/t 


-K 


u> 


Id NO On 10 00 i^ 


M 4^ 


00 


00 


O'Ud 





«^ 


• • 


• 






• 


z \^ * • 




• • 




• 


• 


• 




0* 


2^ • 


o o 


OO 


ON •► 


•K 


+. 


4^ ON M Id VA 


lA 


ON 


b 


00 


00 


00 00 





ST 


1 



93. This 



4i6 Mr. DEhvcen 

93. This laft TABLE 18 the moft important, as it contains a 
dafs of hygrofcopes which poflefs in common the following 
£rft requifites for an hygrometer; ift, that they may indicate^ 
without any illufion, both extreme drynefs and extreme moifiurei 
2dly« that they move couftantly in the fame diredlon as mmp' 
Jure itfelf ; 3dly9 that they move always when moijture changes. 
It (hould feem as if the march of lYttJlIp of born taken leugtb^ 
wife^ from its very decreasing progreflion, came very near that 
of the thin porcupine qnill; but, as I have faid» among the 
fteps of the latter there are accidental retrogradatkns^ and it 
fometimes has a final one ; and I have never obferved that 4i^ 
pofition in the former, which, in its laft fmali fteps, follows 
conftantly the motions of every i>ther Jlip. 

94. The agreement of all the Jlips in this laft refped is a 
very efiential circumftance in hygrometry, as it aflUres iit^ 
that we cannot miftake the cafes when moifiure is extreme in the 
atmofpherg ; a very important point for difcovering the natere 
of many meteorological phceoomena^ ^o^p will create dec^ 
tion in that refpeft; while, on the contrary, every thread 
may deceive in dubious cafes, and even create great error, if, 
unknown to the obferver, it happened to be in the b^inning 
of its elongation. There was, however, a queftion to be de- 
cided in that refpeft, fiamely, whether or not a great moifiure 
in the medium was a caufe of alteration in the march of any 
hygrofcope^ by producing in its fubftance a fudden irregular 
lengthening. That accidental queftion is anfwered in the nega- 
tive by all the hygrofcopes of both claftes : for, in refpedof the 
threads^ inftcad of lengthening fuddenly in that period of mt^f^ 
ture^ they have then a retrograde motion, either continuing 
or only beginning ; and as for the flips^ they, by Itngthening 
in the fame period^ only follow their former laws: the Jlips 

2 which 



Uygrometry. 4.1-^ 

which, comparatively to that of whalebone^ have at fir/l fmall 
Jteps^ and which confeqnently move hi an iiMircafing progref- 
fiou, continue only to tollow that progreffion ; and thofe which 
at firfthave greztcrfh^s, and confequently a decreafing march^ 
have then imM J(eps conformable to their individual law; 
therefore, none of thole hygrojcopes of both clalTes have any 
fuddenjlarty produced by any degree of molflure in the medium^ 
or by the application of concrete water \ each of them fol- 
lows, from one end to the other of its fcale, it own progreffiort ;. 
and in refpedk oi Jlips^ moifture is never extreme in tlie ambient? 
medium^ as long as, in their refpedlive progrejfions^ they have not 
attained their greateft length. 

95. Our common i&v^rfliwrf^r muft then be made of one of 
the Jltps ;. but. with that great diflimilarity obferved in their 
mMrcbety which of them (hall we choofe as indicating the real 
march of moifture f None as yet from that confideration, 
which I do not even think a primary one* It is true, that if 
we trud to the increafes oi weight in thofe fubftances, as being. 
a means of afcertaining the real progrefs of moifture in the 
ambient medium^ the mean rate of (ix experiments of that kind, 
related in this Paper, give the preference to the flip of whale-- 
hone; but this I do not yet coniider as decifive, farther than in 
what relates to the comparative marches of flips and threads ; . 
however, as my reafons of doubt on a more abfolute conclution' 
cannot be exprefled in a tranfltory manner, I mud lay them^ 
afide for th« prefent. 

96. But, as I have faid before, this is not what ought to 
determine our choice on the fubftance of a common hygrometer^, 
fince the obfervations themfelves are diftindl from the confe- 
quences to be drawn from them. Let us fuppofe the cafe 
(which I do not give up) that, with time and refearches, fome 

VoL.LXXXL I ii procefs 



^iS Mr. DE Luc en 

procefs be found by which known quantities of moifture may 
be fucceffively produced in the medium itfelf. The ufe of that 
procefs for bygrometry will be, as M. de Saussure has begun 
to do it, to oblerve, on feme hygrometer^ the fucccffive effcdis 
of thofc knotvn quantities of moifture^ from which may be 
formed a table of the correfpondence between the equal degrees 
of the fcale of the chofen inftrument, and the real quantities 
of moifture in the medium ; and that table will ferve to correft 
as well paft as future obfervatiqns made with that inftru- 
ment. Therefore it matters not what that hygrometer (hall be, 
provided it is convenient in other refpefts. Ltt us then exa- 
mine which of the Jl/ps poflcffes the moft effential properties of 
an hygrometer^ fuch as fliould be in common ufe for compara- 
tive obfervations, and to which confcquently future dilcoveries 
in refpeft ot the real proportions between the quantities of 
moifture itfelf would be applied. 

9^. Steadifiefs is furely a firft requifite for fuch an inftru- 
ment; and in that refpefl no flip comes in competition 
with that of whalebone. That property was the firft motive 
of ray choice ; and as an inftance of it I ftiall only mention, 
that I have juft now plunged into water an inftrument of that 
fort, of above ten years ftanding, which is come to its point 
of extreme moifture as if it had been fixed yefterday ; for, 
without regard to the diftance of obfervations, there may be 
between them a difference of fome tenths of a degrte. Some 
olhtrjlips may be brought to a certain degree of fteadinefs by 
ftudying what is the 'degree oijtretch which they may bear; 
but that attention is nor ncceflary for the flip of whalebone z 
if, for inftance, when its point of extreme moifture has been 
fixed while it was /r^/^A^^ to a certain degree, that ^r^/ri6 is 
5 much 



much increafed, it will acquire fome abibiute length \ but it 
will htfteaaiy again for a new point taken then in water. 

98. Another property of the flip of ^mbalebone^ which at firfl: 
(hould feem contradictory to the former, is its great expanfi- 
hility^ in which alfo it furpafl'es all the fubftancts which I have 
tried* Such a Jlip lengthens above one-eighth of itfelf from 
extreme drynefs to extreme mcjfture^ which produces many ad- 
vantages in the conftrudtion and obfervation of that inftru** 
ment. In refpefi: to obfervation, when it is expoied to the 
wind, the difference between the chords of the arches of its 
bends and its real length is fo fmall, comparatively with its 
hygrofcopic variations, that the indetermination of its index 
will remain confined in a fpace of one or two degrees^ when it 
becomes impoflible to obferve hygrometeri whofe fubftance has 
but little expanfton. Laftly, of all the fubftances which 1 have 
reduced lo Jlips^ none is fo cafily made thin and narrow as 
whalebone. I have found means for producing eafily fuch Jlips 
of it as, with a length of eight inches^ weigh only about -,'^th 
of a grain^ and are thereby as quick as is convenient in other 
refpeflrs. All thofe diftin<aive properties of th^Jlip of wha/e^ 
bone feem to point out zw hygrofcopic fubftance fit for our com-- 
men hygrometer. 

Defcription of the whalebone hygrometer^ 

99. 1 have now oiily to defcribe the conftruftion of that inftru*- 
ment as Ihave fixed it after a long experience. The^^. i. (Tab. 
IX.) (hews its form for common ufe. Some of thofe inftrumenta 
arc of the fame fize as the/^«r^, and they may eafily be made 
fmaller, hut commonly they are half as large ag/^in in every di- 
menfiour Their frame w ill fufficiently be known from the Jigure^ 

I i i a therefore 



4.20 Mr. DE Luc on 

therefore I (hall coniine myfelf to the defcription of fomc par- 
ticulars. The Jlip of whalebone is reprefented hj a^b\ and at 
its end a is fcen a fort of pincers^ made 6nly of a flattened 
bent wire, tapering in the part that holds tht Jlip^ and preflcd 
hy a fliding ring. The end b is fiKed to a moveable bar r, 
which is moved by a fcrew for adjufting at firft the index. The 
end a of the Jlip is hooked to a thin brafs wire ; to the other 
end cjf which is alfo hooked a very thin filver gilt lamina^ that 
has at that end //W^rj fimilar to thofe of the l^/]^, and which 
is fixed by the other end to the axis by a pin in a proper hole. 
Thc./pring d, by which the Jlip is ftretched, is made of iilver 
gilt wire ; it afts on the Jlip as a weight of about 12 grains, 
and with this advantage over a weight (belides the avoiding 
fome other inconveniencies of this) that, in proportion as the 
Jlip is weakened, in its lengthening by the penetration of 
moiftiire, the Jpring^ by unbending at the fame time, lofes a 
part of its power. The axis has very fmall pivots^ the 
Jhoulders oi which are prevented from coming againft the frame, 
by their ends being confined, though freely, between the flat 
bearing of the heads of two fcrews^ the front one of which is 
feen near^I The fedlion of that axis^ of the fize that belongs 
to vijlip of about 8 inches, is reprefented in ^g. 2. ; the Jlip 
a<3:s on the diameter ^, a^ and the Jpring on the fmaller dia- 
meter ^, b. 

1 Qo. Another condru&ion of the fame inftrument is repre- 
iented, of half its dimenfions, by ^^. 3. (Tab. X.) The eflential 
parts of that hydrometer are the fame as in the other ; therefore I 
ihall only mention the differences adapted to the ufe of fixing it 
out of a window. Tht Jigure repreients the manner in which 
it is fixed, with its dial turned half-way towards the obferver, 
.by a proper head of the hooks which hold it at the top and the 

bottom. 



Hygromefyy^ 421 

i3ottom. The fleady part of the inftrumcnt k reprefented by 
^'g. 4. ; it is partly an half tube, cut longitudinally through 
<he axis, and having fidewife two vertical rows of large holes. 
A whole tube goes over that half one ; for which purpofe the 
piece ^, a^ is taken off by unfcrewing the female fcrew ^ which 
belongs to the part J; this lafl is a fmall open tube, cut out- 
fide in fcrew. The large external tube has alfo two vertical 
rows of holes, at fuch a diftance from one another, that, when 
one of them correfponds to one of the rows of the half tube^ 
the other is in front. The two oppoiite pofitions that tube can 
be brought to are in order that the inflrument may be placed 
either fide of a window, and each of thofe pofitions is deter- 
mined by one end of a cut at the bottom of the tube in j, ^g^ 
3, which then holds againft the fteady pin r, ^g. 4. The rows 
of holes of the tube are to be turned towards the room, to 
prevent the rain from falling on xYi^Jlip ; and the dial being 
inclofed in a box with a glafs in front, no rain can get into the 
inftrument. It muft alfo be fixed in a place not much expofed 
to the fun, or be icreened from it without preventing the circu- 
lation of the air. The communication of the Jlip with the 
external air through the rows of holes and the open bottom d^ 
fg^ 4* is fufficient for that dafs of obfervations. By the man* 
ner of its being hooked, it may be eafily taken off for carrying 
elfewhere ; arid, if a quick obfervataon is wanted, the tube alfo 
may eafily be taken off. 

I have the honour of prefenting one of thofe inftruments to 
the Royal Society ; and, as it is very defirable that fome hygro- 
meter be added to the other meteorological inftruments ufually 
obferved, I wi(h this may deferve a place ia their Obfervatorjr 
tax that purpofe. 



FhOos, Ihtw. Vol USaJ. Tab. JX.PuitA. 




Fhtlos. rrans. Vol LXXXI. Tad, X./f.4S,^, 




•^OLfi/re. Jc. 



PRESENTS 

MADE TO THE 

ROYAL SOCIETY 

From November 1790 to June 1791 ; 

WITH 

The NAMES of the DONOR S. 



«790 
Nov. 



. Prcfents. 
4. The Nautical Almanacs for the Years 1 793, 
1794, 1795* and 1796. 4 Vols. Lon- 
don» 1790. 8^ 

A Colleftton of Ordinances and Regulations 
for the Government of the Royal Houfe- 
hold. London, 1790. 4^ 

TranfadHons of the Society for the Encou- 
ragement of Arts, Manufa6luresy and 
Commerce, Vol. VIIL London, 1790. 

8^ 

Report of the Committee of the Highland 
Society of Scotland, on the Subje^k of 
Shetland Wool. Edinburgh, 1790. ^ 

Traite Analytique des Mouveroens apparens 
des Corps cclefles, par M. Dionis du Se- 
jour. Tome II. Paris, 1789. 4* 

N. J. Jacquin Colledanea* ad Botanicam, 
Chemiam et Hidoriam Naturalem. Vol. 
HI. VindobonsB, 1789. 4° 

Cautions to the Heads of Families, by A. 
Fothergill. Bath, 179O. 8^ 

Machine hydraulique d*une nouvelle inven- 
tion, parT. Wc3u Nantes, 1787, 8"* 



Donors. 
The Commiffioners of 
Longitude. 

The Society of Anti- 
quaries. 

The Society for the En- 
couragement of Arcs, 
Manufactures, and 
Commerce. 

The Highland Society 
of Scotland. 

M. Dionis du Sejour, 
F. R. S. 

ProfeiTor de Jacquin^ 
F.R. S, 

Anthony Fothergill, 
M. D. F.R. S. > 
M. Wcx. 

1790 



I 4*4 J 



1790 Frefenu* 

Nov* !!• Memoirs of the LiteraTy aod Pbilofophical 
Society of Mancheftcr. Vol. HI. War» 
rington, I790» 8° 

Medical CommuaicatioDS,. Vol. II,. Lon- 
don, 1790. 8® 

A Treatife on the Digeftion of Food, by 
G. Fordyce. London, 1790. 4** 

Linnaean Zoology, by G. Sha^r; the Fi- 
gures bjTj. Sowerby. N** I. London, 
1790, 4"" 

The Naturalift's Mifcell4ny, byG. Shaw; 
the Figures by F. ?• Nodder. Vol. I. 
London, 1790. 8^ 

; Frincipcs fur les Mefures en Longueur et 

en Capacite, fur les Poids et les Moo^ 
noicsy par M. Bonne. Paris, 1790. 8° 

Frseledio Academica fimpliciores et falu. 
briores comprehendens de Febribus no- 
tioncs, a Jof. Pinilla Vizcayno. Com- 
pluti, 1790. 4° 

l8fl Nova A£U Academiae Sclent lanHn Impe* 
fialis Petropolitanae. Tomus V. Pe* 
tropoli, 1789. 4"" 

Zwo abhandlungen iiber die Nutritions 
kraft, welche von der Kayferl. Academie 
der Wiflenfchaften in* Sr. Peteriburg den 
Freis getheilt erhalten haben, St. Pe* 
terfburg, 1789. 4** 

Co'mmentahi de Rebus in>Scientia Natu- 
rali et Medicina geftls. Voluoien XXXI. 
Lipfiz, 1789- 8° 

Obfervations on Poifons^ by T^. Houlflon. 
Edinburgh, 1787. 8° 

25. KongU Vetenikaps Academiens Nya Hand* 
lingar, Tom. X. for 1789, 3d and 4th 
Quarter; and Tom. XL fori 790, 
I ft and 2d Qiiarter. Stockholm. 8^ 

Maniera di migliorare e dirigere. i Pallonl 

aerei, inventata e dimoftrata dai Fra* 

telHGerli. Roma, 1790* 8° 

•ec, 9* A Portrait of Dr. Bradley, late Aftrono- 

mer Royal and F. R. S. 

A Portrait of the late Benjamin Franklin, 
LL.D. F. R. S. 

Meteorological Journal kept at Bengal, by 
the late Colonel T. D. Pearfe, from June 
a8» 1787, to April 9, 1789* MS. fot; 



Donors. 
The Literaiy and Pbilo*^ 

fophical Society of Man- 

chefter. 
The Society for promoting 

Medical Knowledge. 
George Fordyce, M. D. 

F. R. S. 
George Shaw, M D.F.R .S. 

and Mr. James Sowerby. 

George Sha:w,M.D.F.R,S. 
andMr.F. P. Nodder. 

M..Bonne. 



Profeflbr Pinilla Vizcayno^ 
of Alcala. 



TKe Imperial' Academy i»f 
Sciences of Peteriburg. 



Mr. Hurlock, F. R. S. 



Mr. Houlfion. 

The Royal Academy of 
Sciences of Stockholoi. 



Sign. Agoftino Giofeppe e 
Carlo Giofeppe Gerli. 

The Rev. Mr. Peach. 

Caleb Whitefoord^ Efq.. 

F. R. S. 
Sir Jofeph Banks, Bart. 

P. R. S. 

»79d 



1790 
Dec, 



23- 

1791 
/ill. 13. 

SO. 



[ 4*5 J 

Prcfents. 

Oratio Anniverfaria in Theatro Coll, Reg. 
Med. Lond, ex Harveii infiituto habita a 
J. A(h. Londini, 1 7 90. 4'' 

Iniex Orntthologicus, ftudio Jo. Latham. 
Londiai, 1790. 2 VoU. 4*^ 

Extrait des Obfervations Allronomiques et 
Phyfiqiics fiifc& ^ FObfcrvatoirc Royal en 
rAnoLCiySg. 4** 

Geographic des Grec« analyfee^ par M. 
Goffclin. Paris, 179O. 4° 

The- London Medical Journal. Vol. XI. 

London, 1790. 8"* 

A Narrative of the 6uil<fing. and a De- 

fcription of the Conftrudion, of the 

Edyftone Lighthoufe with Stone, by J. 

Smeaton. London, 1791. f^l* 

Journal of a Voyage to New South Wales, 

by John White, £fq. London, 1790. 



ay. Magnetic Atlas, or Variation Chart, by 

J. Churcbman. 
An Explanation of the Magnetic Atlas, or 

Variation Chart, by J. Churchman. 

Philadelphia, 1790. 8^ 

f eb« 3. Obfervations generales . fur la Refpiration 

et fur la chaleut animalei par M. Se« 

goin. 4^ 

Rclacion de las Epidemias, que han afli* 

gido a la Ciudad de Cartagena, por D. 

Mart. Rodon y Bell. Cartagena, 1787* 

Difcurfo que para dar Prindpio a los pri« 
jscroaExercicios Publi^os de la Botanica 
dixo el D. D. Mart. Rodpn. Cartagena, 

1785- 4' 

The Antiquaries Mufeiims by J. SchDeb- 
belie. NM. 4' 

17. Ubellus de Natura, Caufa, Curationeque 
Scorbutu Audtorp N. Huhne. Lon- 
dini, 17^8. 8^ 
A Trcatifc on the Puerperal Fever, by N. 
Hulme. London, 1772. 8"^ 
Oratio de re Medica cognofcenda et pro- 
. . movend^^AudloreN. Hulme. Londini, 

^ /777- 4V 

Vox.. LXXXI. K k k 



Donors. 
John Afh, M.D. F.R. ?. 



Mr. Latham, F. R. S« 
M. de CaflSni, F. R, S. 

M. Goffelin. 



Samuel Foart Sinsnons, 

M. D F.^.S, 
John Smeaton, £fq.F.R.S. 



Thomas Wilfon Efq. 
Mr. John Churchman. 



M. Seguin. 



Don Maotin Rodon y BelL 



Mr. Schnebbelie. 
Nathaniel Hulme, M. D« 



1791 



[ 42(5 ] 



179^ Prerents. 

Feb. 17* A fafe and eafy Remedy, propofed for the 

Relief of Stone and Gravel, &ۥ by N. 

Hulme. London, 1788. 4"^ 

Mar. io« Letters on the Elements of Botany, by J. 

J. Rouflcau, tranilatcd into Englilh, 

with 24 additional Letters, by T, Mar* 

tyn, London, 1791. 8"^ 

Thirty-eight Plates, with Explanations, 

adapted to the Letters on the Blennenls 

of Botany, by T. Martyn, London, 

1788. 8" 

ly. A Treatifc of the Plague, by P. Ruflell. 

London, 179 1. 4^ 

14. Obfervatiooes Siderum habitat Pifis ab 

Anno 78 ad Annum 82 vertentis S^bculi, 

a Jof.Slop deCadenberg. FiGs, 1789. foL 

31. A Treatifc on the Angina Feaoris, by "Vf. 

Butter. London, 179 1. 8° 

Apri} 4« Icones felefiae Plant^r^iitn, quas in Japonia 

collegit et delineavit Eng. Kaempfer. 

Loadiai^ 1791. fol. 

An hifiorical Developement of the pcefent 

politkal Conilitution of the Gemaank 

Empire, by J. S. Piitter. TninlUted 

from the Germaa, with Notes, by J. 

Domfoxd* London^ 1790. 3 Vote. 

8^ 
A Difcourfe on the Principle of Vitality, 
by B. Waterfaoufe. Bofloo, 1790. 4"* 
14* Recherches fur cette Quetion : la Cbalettr 
natnrellc de rHomme peut-«Ue ktxt 
confideree comme un Terme fixe ? par 
M^'Gauflen. MonlpelUery ijtj. V 
Differcation fur le Tbcnaomiti^ de Reau- 
mur, par M« Gaiiftn* Beziers^ 1789. 

May 5. Pbarinacopceia CoUcgii Regalia Medi^nm 

Londinenfis. Loniioi. 8^ 

Jka Accouat ^ the Life and Writiftgi of 

Thomas Day, Ef<|, Losdoo, 1791.8?* 
Elements de TArt de la Te inture, par M. 

BertboHet. Tomes n. Paris, 1791. 8^ 
A fliort Account of a Paflage from CUw 

late in tke Scafon. London, 1788. 4*^ 
Charts of the China NavigatioD, by G. 

Robertfon. London, 1^88, f^. 



Donors. 
Nathaniel Hulme, M. D. 



The Rev* Thomas Martp^ 
B. D. F. R. S. 



Patrick RuCell, M. D« 

F.R.S. 
Profbflbr Slop, of Pifa. 



William Butter, M. D. 

Sir Jofeph Banks, Bart. 
P. R. S, 

Jofiak Doniftrd, LLJ>* 



Prof. Wateriiou&, of Cani*^ 
bridge in Amarica. 

M. Gaufleo,. of Moiit«» 
pellier. 



The GoHege of (byficianSr 
James Keif, Sf;. KH. S. 
M. Btrtfamletj F« R« S». 
lir. George B^obertibn.. 



mf 



[ 4»7 1 



\ 



t79t Prerents. 

May 5. Chart of the China Sea, iQctading the 
Fhilippina^ Mollucca, and Banda Iflandt^ 
by G. Robertfon, 1791. 
Memoir of a Chart of the Chhia Sea, by 
G. Robcrtfon, lyoi* 4^* 

12. Tranfadtions of the Royal Irifii Academy, 
1789. Dublin. 4" 

Aftronomifches Jahrbuch' fur das Jahr 
1793, ^®" J* EBodc. Berlin, 1790. 8° 
26. lUuftrations of BritHh Hiftory, Biography, 
" and Mannecv, exhibited in a Series of 
original Papers, by E. Lodge. 3 Vols. 
London, I 79 I. 4^ 

Lettre de M. Van Marum, contenant.la 
Defcription d*une Machine ^le^rique, 
conftruite d'une mani^fe nonvefle. 4^ 
ObfiervatioAs ||?nera}es fur les Senfations, 
par M. Seguin. 8' 

June a» Saggio di Litologia Vefuviana, dal Car. 
'. G. Gioeni. Napofi, 1790. 8"* 

BefiioHnung der Hohen der bekanntem 
Berge. des Qantoo Bern, ?on J. 'G; 
Tralles. Bern, 1790. 8^ 

9. A Print of John Smeaton, Efq. F. R. S. 
engrared by W. Bromley. 
Obfenrations on the Difeafes, Defefls, and 
Injuries in all Kinds of Fruit and Foreft 
Trees ; with an Aecoont of a Cure in- 
Tented by W. Forfyth. London, 179 1« 

Effiii d'une Claffiftcation des Coideurs. 

MS. 4^ 

a3. The Philofophy of Ancient Greece invtfti^ 

r^r - ^aled in its Origin and Progrefs, by W. 

Anderfon. Edinburgh, 1791* * 4^ 

July 7* Icones flirpium rariorum Defcriptionibus 

' iiliifttatse, Auaott R. A. Saltlbury. 

Londini, 1791. A)K 

14% Oriental Repertory, pobHiied^by A. Dai- 

lymple^ N°L London, i79t. 4? 

Medical Fada aod Obfemitio&8« VcL I. 

London, 1791. ' 8"* 

A Whalebone Hygrometer. 



Donors. 
Mr. George Robertibi 



The Royal Iri(h Academy* 
Mr. J. E. Bode, F. R. S^ 
Edmund Lodge, Efq. 



Martinus Van Marum, 
M. D. of Harlem. 

M. Seguin. 

Cavaliere Giufeppe Gio* 

eni. 
Frofefibr Tralles, of Bern. 



Alexander Aubert, Efq. 

F. R. S. 
Mr. William Forfyth. 



M. T. F. Opitr, of Tschav 

ilau in Bihemia. 
The Rev. Waiter Ander* 

fon, D.D. 

Richard Anthony Salif* 
bury; Efq. F. R. S.' 

AlexanderDlilfyitipfe,Efqi 

F.R. S. 
Samuel Foart Simmoo8|< 

M. D. F. r1 S. 
J. A. De Luc, Efq,F.R»&i 



C 4»« 3 



■■■■■■■ ■■ »■■■ ■ " I ■ -■» .^ l.»i ,l■^■l. w ■ ^^ .^ .iipw 



A N 

I N D E X 

TO THE 

EIGHTY-FIRST VOLUME 

O F T H E 

PHILOSOPHICAL TRANSACTIONa 

A. 

ABSTRACT of a regifler of the barometer, thermometer, and rain, at Lyndoo 
in KttClandihirei for the year 1789, p* 89, 
Jcc9itfU cfionyt appearances attending the converfion of call into malleable iron, p* X73* 
.Acidy nitrpus, thptigh coniiftiug of the fame elements with pure water, containa « 
greater proportion of dephlogifticated air, p« ^19. Pbofphonc acid, an ingredtent in 
James's powder, p. 34^. 
Air^ extreme moiflure exifts in, p. 19. The maximum of evaporation in a mafi of 
inclo(ed air, far from being identical with the maximum of moiflure, p« ao. Obfer- 
vatinn on the production of heavy inflammable air, p, 176. Fixed air contaiot a 
jnocfa larger portion of oxygene than of charcoal, p* 177. OUervatioos ou the de* 
compoiition of fixed air, p. 182. Fixed air produced by charcoal, ibid* Vital air 
more llrongly atrraded by charcoal than by phofphorus, p. 183. Experimentt 
relating to the decompofition of dephiogdicated and inflammable airs, p* aij- la-* 
flammable air procured from iron by means of fteam, p. Ji6. Nitrous acid, thougk 
confiding of the fame elements with pnre water, contains a greater proportion of 
dcphlogidicacu'dair, p«2i9. In a flagnant air every evaporating fubftance has an 
atmoff here of extreme moi&are, pt 403* 

AkM:^ 



r. 429 } 

Alc^hoU fugsrlias no renfi'ilc afSnity wi^h, p. ii. Alcohol, having entered fagar, by 

means of its capillary pores, evaporates, and leaves the fugar feDlibly as it was 

bcbre, ibid. 
Aleppo.^ dii^ance between it and BulTorah, p. 137. 
Ambergris^ on the proda£lion of, p. 43. Ambergris found in a fpermaceii whale, ibid. 

Mod likely to be found iii Gckly w> ales, p* 47. 
Anglesy defciiption of a finaple micrometer for meafuring fmall ones with the telefcope, 

p. 283. , 

Antimvnialls^ puWis, expt-riments. on, p. 34^ 
^//MOMy aod antimonui calces, various experiments on, p. 3J1. Antimonia! calx, an 

ingredient in James's powder, p. 345. Salphur of aatimoQy no way necedaxy to 

the formation of James's powder, p. 360. 
Arch. Coniiderations on the convenience of meafaring an arch of the meridian, and 

of the parallel of longitude, having the Qbfervatory at Geneva for their commoA 

interCeftion, p. 1061 
Atmo/fheric eledtricity, meteorological journal principally relating to^ p.i8p 

B. 

Barker^ Thomas, abftraA of a'regHler, for the year 1789, of the barometer, thermo- 
meter, and rain, at Lyndon in Rntlandihire, p. 89. 

Barometer^ 8bftra6t of a regifter of one, kept at Lyndon in Rntlandihire, for the year 
1789, p. 89. 

Bafaltes and granite, obfervations on the affinity between, p. 48. Bafaltes and granite 
gradually approach and change into one another^ p* 50. Feldipath, ihoerl, andmica^ 
fttbdances common both to bafaltes and granite, and tend to eflabiiQi the near rela* 
tion between thefe two kinds of rock, p. 54. Bafaltes and granite fo involved jq 
one another, that they are fnppofed to have undergone the fame operations of nature 
St the fame time, p. j8. ^ 

Beddo^s^ Dr. on the affinity between bafaltes and granite, p. 48. On fbme appearances 
attending the converfion of call into malleable iron, p* i73« 

Bujfwahy its diftance from Aleppo, p« i37» 

G. 

CacMongy Hydrabad Tabalheer refembtes, p. 369^ 

Ctf/r^/, 'antimonial, experiments on, p* 35i« 

Caltuliy human, experiments on, p. laj. 

Camelsj on the rate of travelling, as performed by; and its applicatron, ai a (cafe, t^ 

the purpofcs of geography, p. 129. A cam«rs load 500 or 600 pounds, p. 136. 
Capella, a ftar of the firft magnitude^ culminatea between the zenith of Geneva and 

St. Jean Mauriennei p. ii5» 

X CafiOary 



E 430 ] 

Captllaty pores, water enters fugar by means of, p. ir. Alcohol enters fagar bjr At 
fame means, ibid. The penetration of animal fubftances produced by the bcx&tf 
of capillary pores, p. i a. 

Cafts ]Q which horny excxefcences have appeared on the human body, p. q6. 

Cavalioj Mr. Defcription of a iimple micrometer for meafaring fmail angles with thtf 
telefcope, p. 283. 

Cau/ewayy Giant's, many of its pillar conilft of fine-grained, dark*coloured whin« 
(h>ne, p-51. 

Chalky a great deal of chalky ground in the foathern parts -of England, p. iSt. Vein 
of chalk runs from the fea in Devoiffhire, along the (bnthern counties of England to 
Dover, ibid. Another vein parts off from that about Reading in fietkfliire, and 
continues its courfe by Dunftable, Baldock, and Gbgmagog Hills, to the fea in Nor* 
folky ibid. Confiderable quantities of chalk in the wolds of Yorkfliire, ibid. Bed 
^f chalk difcovered near Ridllngton in Rutland, ibid. Chalk about Rldlington 
harder than chat of the fouth of England, ibid. 

Cbermes Lacca, account of, p. 228. Frequently adheres to the branches of the Mlmofii 
cinerea, ibid. VaU qnantities of exceedingly fmall animals oblerved upon the lac 
and branches, ibid. Defcription of the malehic infect in its perfeft ftate, p. 231. 
Description of the female lac infe^ in its perfe^ date, ibid. Mr. Hellot's procefaibr 
extiafUng the colouring matter from dry lac, p. 233. 

C^Jideratkns on the convenience of meafnring an arch of the meridian, and of the 
parallel of longitude, having the Obfervatbry of Geneva for thdr common imer* 
iefibn, p. ic6. 

D. 
Dalhyy Ifaac, on the k)ngttudes of Dnnkirk and Paris from Gfeeowicfa, dcdoced fi«m 

triangular meafarement, fuppofiog the earth to be an elUpfoid, p. 236. 
DefM^r^eaud air. See Air. 
Deforjptm of a fimple micrometer for meafttring fmalf angles with the tdcfcopey p. 

265. Ddcription of the whalebone hydrometer, p. 41^ 1 

Dev9^fl?ire^ vein of chalk runs from the fea aoaft of, sdong the feuthem conntiea of 

Eng^nd to Dover^ p. 28N A mn of chalk runs (torn the &a coafi of Devonlhfae 

to the fea coaft of Norfolk, ibid. , 

Difim^ between Aleppo and Boflbrah, p. i j^i 

Dvutr^ vein of chalk, which runs from Dnvonfluro, torftitAatet at, p. j8r» 
Drymfs^ abfolMc, can only be prodoced by fire, p. i. QUervntioiis anaUUtfte Ay- 

nels, p. 2. Diynefs prodoced by pot-aih, p. 4.. Bbintof diyAefrcapafaloaf Aw'^ 

tion by lime» p. j. 
Dunkirk^ its longitude from Greenwich dedsced b^m tiiao^ilar mc fMnmm, fi^ 

f oJCng the earth to be an-ellipibid, p. 2369 



[ 431 3 



EleSricity^ meteorologicd journal, princi^Iy nhttng to atmofpberict kept at KolghtH 
bridge, p. 185. Defcripdoo of an in^lruBienc for collecting atoiorpberic eledricity, 
ibid. Rtaarks on fome phaenomena exhibited by a rod on Aug. 31, 1789, p* 11 1. 

EvapcreuUu^ the caufe of bygroliwpic bodies lo£ttg part of tbeir moiflare, p. 2. £:(pe- 
riments on tbe maximuin of evaporadon, and its correfpondcnc& with the maximum 
of moiftare in a inediain, p. 17. The maximum of evaporation in a mafs of 
inciofed air, far from being identical with the maximam of moifture, p, ao. In a 
ilagnant air every evaporating fabftance has an atmofphere of extreme moi^rc^. 
p. 403. 

Excrefctnctsy obfervadons on certain ones of the bnman body, p* 9$. 

Exferimenu on hygrometry, p, 2^42. Experiments on abfolute drynefs, p. 2, On extreme: 
moiflare, p»io. On the maximum ofevaporadon, and its correTpondence with the maxi* 
mum of moifture in a medium^ p. 17* On two diAindt clalTes of hygrofcopes, p. ao* 
On the fcale of the hygrometer between the two fixed points, p. 24. On the compara^ 

- tive changes of weight and dimenilons of fome hygrofcopic fubflances, p.. 27. On the 
xecoil of hygrofcopic threads, p. .39. On the converlion of cad into malleable iron, p* 
173. CondufioDB drawn from experiments on iron, p. 175. . Experiments relating to 
the decompofition of dephlogifticated and inflammable airs, p* a 13*. Inflammable air 
procured by means of fleam, p. ai6. Experiments on human calculi, p. 223.. 
Experiments and obfervadons to invefligate the compofidon of James's powder, p. 
317. Experiments on the fenflble properdes of James's powder, ibid. On its (pe- 
ciflc gravity, p.. 31 8. Experiments on the efiedts of fire on this powder,. ibid. Ex- 
penment fliewing that andmony, mixed with earthy matter, ia ufed in the compofi- 
fion of James's powder, p. 320. Expeiimenti with di&ient menflrua applied to 
James's powder, ibid*. Experiment fliewing the proportion in which James'a pow« 
der diflblves in water, p. 324. Eaqperiment with marine acid applied to Jamts'a 
powder, which had not been expofed to the a%on of nitrous add, or any other 
aenftrunfflf.p. 344. Experiments on James's powder with fixed alkalies, p. 34$. 
Synthetic experiments on James's powder, ibid. Experiments 00 iheFolvband. 
monialis, p. 349. Various experiments on andmonial calces, p. 351* Chendcal- 
experiments on Tabaflieer, p. 368. Experiments on Tabaflieer, treated with water^ 
p. 370. With vegetable coloivs, p. 37.1. At the fire, ibid. With acids, p. 373». 
With liquid alkalies, p. 375. Widi dry alkalies, p. 379* Widi other fluxes, p.. 
380., Table of experiments on comparadve changes in the weight and the length, 
of the fatne fiibflanceby increafing moiflure, p« 411. 

F. 

EeJJ^tbf a Cttbftance common both to bafaltes and granite^ p. 54^ 

Fffjwr fvwdcrs^ receipts for making, p* 34^1 347» a 



t *3* 3 

Firc^ confidered as the caufc of heat, the ODiy agent by which abfolute drynefi cin be 
imrocdiaicly produced, p. i. Fire capable of prodacing my required degree of 
compadoetf, as lavas abundantly flttw, p. 55. The effects of fire on James's pow- 
der, p. 3 18. Fire powefful in the change of the coloar of bodies, p. 362. Fiie the 
caufc of heat, p. 402. 

Fixed air. See /iir* 

Flints^ rows of, in a chalk-pit near Ridliogton in Rutland, p. 281. Flints about Rid« 
lin^ton not fo black as thofe of the fouthcrn counties, but veined, ibid, 

F\fieU\ in Hampfiiire, abftradof a rcgiller of rain kept at, for the year 1789, p. 89. 

G. 

Geneva. Confiderations on the convenience of meafuring an arch of the meridian, and 
of the parallel of longitude, having the Obfcrvatory of Geneva for their common 
interfev-tion, p. to6. Capella, a i^ar of the firft magnitude, culminates between the 
zeniihs uf GcDCva and St. Jean Maurienne, p. 115. 

Geography, On the rate of travelling, as performed by camels; and its application at a 
fcale, to the purpofes of geoj^raphy, p. 129. 

Giant's Caufe^ay^ many of its pillars confifl of fine-grained, dark-cobnred whiofbne^ 
p. 51. 

Granite and bafaltes» obfervationi on the affinity between, p. 48. Almoft all granires 
melt into a black glafs, p. 60. Granitic iavai are granite rocks fafed, p. 63. Mal- 
vern Hills, compofed of granite, p. 6^. 

Greemuich^ the lorgitude of Dunkirk from, deduced firom triangular meafurement, fup- 
pofiDg the earth to be an eilipfoid, p. 536. Longitude of Paris from Greeawichp 
ibid. 

H. 

Heat^ at its maximum in a body, when it is incandefcent, p» j. Heat caufid by 
fire, p. 40s. 

HerfcheU I^r. on nebulous ftars, p. 71. 

Homey Everard, on cerain horny exert fcences of the human body, p* 9$« 

Human body, obfervations on certain horny ezerefcences of, p. 95. The eafe of 
Mrs. Lonfdale, p. 96. The cafe of Mrs. Allen, p. 98. 

HyJrahad Tabalheer, experiments on, p. 369. RefemMes Cacholong, ibid. 

Hygrometer^ fundamental propofitions for the conflrn£Hon of an, p. i. Abfohltediy- 
nefs can only be produced by fire, ibid. Extreme mdiflnre can only be produced by 
means of water, ibid. 16. Obfervations on abfolute drynefs, p. a. An bygrofcopic 
body cannot lofe any part of its moifture, but by evaporation, ibid. Drynefs capable 
of fixation by lime, p. 5. An bygrofcopic body, which is brought to incandefcence, 
cannot contain any evaporable water, p. 9. The point of extreme moifture of an 
hygrometer known by the excefs of water, p« 17. Obfervations on two difHnd 

daires 



t 433 ] 

* clafies of lygrofcopes, p. 20. Obfenratbns on the fcale of the hygrometer between 
the two fixed pointSy p. 24. Experiments on the comparative changes of weight and 

' dimenfions of fome hygrofcopic fubftanceSi p. 27. Experiments on the recoil of 
hygrofcopic threads, p. 39. Hygrometers ▼arioafly afie6ted by fcattered atmofpheres 
of extreme robifture, p. 401. Steadinefi the firft requifite for an hygrometeri p. 
418. Defcription of the whalebone hygrometer, p. 419. 

I^grcmctiyf obfcnratiohs on, p. i. 389. 

L 

James's powders, experiments and obfenrations ta invcftigare the compoiition of, p. 3 r^.^ 
Its nature hitherto unknown to the public, ibid. Senfible properties of the powder, 
ibid. Smooth to the feel, wich fom^ rather rough particles, ibid. Gritty in the 
mouth, p. 318. Perfedly inodorous, ibid. On the fpecific gravity of James's pow- 
der, ibid. Much heavier than any of the common earths and dones in a pulverized 
fUte, ibid. The effects of fire on this powder, ibid. Antimony mixed with earthy 
matter, found by experiment in James's powder, p. 320. Experiments with dif- 
ferent menftrua applied to James's powder, ibid. The proportion in which James's 
powder diifoWes in water ihewn, p. 324. Condufions. drawn from experiments on 
James's powder, p. 325. Experiment with marine acid applied to James's powder^ 
which had not been expofed to ihe adion of nitrous acid, or any other menftrunm, p. 
344. Fhofporic acid, lime, and antimonial cahr, ingredients in James's powder,, 
p. 34 j. Experiments on James's powder with fixed alkalies, ibid. Sulphur of anti* 
mony no ways neceiTary to the formation of James's powder^ p. 360. The ingre-^ 
dients made ufe of in the formation of James's powder enumerated, p. 367, 

Jnjinite feries, obfenrations on, p. 146k New method of invefligating the tfums of infi* 
nite feries, p. 29 j. 

Jnfiammable air, obfervation on the production of heavy, p. 176. Experiments relating 
to the decompofition of inflammable air, p. 213. Inflammable air procured from 
iron by mean) of fleam, p. 216. 

Itifefi. Defcription of the male lac infed in its perfect ftate, p. 231. Defcription of 
the female lac infcA in its perfed ftate, ibid. 

Journal^ meteorological. See Meteorological Journal, 

Iron, Account of fome appearances attending the converfion of ca(( into malleable, p. 
173. Condufions drawn from experiments on iron, p.. 175. Grey iron contains a* 
large portion of plumbago, p- 177* 

Jvoryf the temperature of water has a fenfible effedt on the expanfion of, p. 1 5. 

L. 

Lac, See Chermes Lacca, 

Lamhetbt South, abftra6t of a regifler of rain kept at, for the year 1789, p. 89. 
Lanct Timothy, on human calculi, p. 223. 
Vot. LXXXr. L LI Lavas,. 



( 434 ] 

L^^uss^ abuodaody flieir# Aat Ire ii capable of ptodtdiig wof reqoiicd legrae of i 

paAne&y p. $$. Granitic lavas are granite rocks fuftd, p. 6}. 
Life, On the method of dectrminiog, from the real probabiliciet of life, tbe vataes ef 

contingent reveriioni in which three Kves are involved in che furvivoiflrip, p« 146. 
Lime^ an ingredient in James's powder, p. 34$. 
Lrfi of Prefenti, p* 423. 
LcngituJc, confideratieos on the convenience of enaforing an arch of the panOel of, 

( • 106. 
Longitudes of Dunkirk and Paris from Greenwich, deduced from ttiaagular sBeafu^ 

nient, fappofing the canh to be an ellip(«id, p. a j6« 
Litc^ J. A. de, on bygrometry, p. t. 389. 

IL 

A&r/V, Mr. on Tabafheer, p, j68, 

Malvern Hilh^ compofed of granite, p. 6(» 

Meteorological Jowmaly relating fo atmofpheric eleSrictty, p. r8(. See EkBrkh^, 

■ kept at the Apartments of the Royal Society, for January 1790, 

App. p. a. February, p, 4. Marvh, p. 6. April, p. 8. May, p. xo. Jane, p. is. 

July, p. 14. Augaft, p. i6« September, p. z8« Odober, p»30. NevcnWr, p* 

as* December, p.. 14* 
Ji^ca^ 8 fubilanee common both to bafakes and granites, p. $4. 
Micrometer^ defcription of a fimple one fer metfuriog fmatl angles with t&e leleftope, p* 

283. Telefcopical micrometers, divided into two daflb, ibid. 
Milfy 'wey^ con€fb entirely of ftars, p* yt. 
M^fture^ in hygrolcopie bodies, can only be produced by means of water, p. t. Iff> 

grofcopic bodies cannot tofe pan of their moiilure, but by evaporatbn, p. a. Quick* 

lime poficfts a peat capacity fer moifture. p. 4. ObierTations on extreme OMiiffDic^ 

p. 10. Mviftore, a quantity of invifible water, either evaporablej or evaporated, p» 

14* The maximum of moifture known by tbeeaoefa of water, p. 17. fiartreme 
. moiflare ezifts in the atr, p 19. The idea of two Ibrts of extreme moiftuie withmsK 

foundacion, p. 401* In a (tagnaot air every evaporating fubfhmce has an Btmoi|ibere 

of extreme moiflart, p, 403. 
Morgan^ Mr. on the method of deteroMning, from the real probtbifiries of Bfis^ 

the vahies of contingent reverfions in which three fives are.isvotftd ta the fiir- 

vivorihip, p. 246* 

N. 

Xcbuhut ftars, obfervarions on, p. 71. Diffufed nebulofities oUeneA akua dieci»i 
ftelJation of Orion, p» 85. 



[ 415 1 

p. 

faris^ itt longitude htm Gf eenwich dedac«d from triangtdtf meafurtmcn^ %pofiog 

the earth to be tn eUipibjdy p* ti(>* 
Pearfin^ Dr« on the compoficion of Jamca*a powderi p« 317* 
Pboffbwusy not obtainable by pafling marine acid through a compound of bones aiid 

charcoal, when red-hot, p. 1 84. The attradion of phofphorus and lime for vital air 

exceeds the' at traflion of charcoal by a greater force than that arifiog from the attrac- 

tioQ of marine acid for liipe^ ibid. 
PiHet^ Mark Augullus, on the conyenience of meafuring an arch of the meridian^ and 

of the parallel of longitode, having the Obfervaiory of Geneva for their commoa 

interfedioo, p. io6. 
Pvres^ capillary, water enters fugar by means of, p. lu Alcohol enters fugar by 

the fame means^ ibid. The penetration of animal fubilances produced by the &cqlt/ 

of capillary pores, p. la* 
Pu-ajh^ with fome other alkaline fubtfancet produce drynefs, p. 4. 
PviDder. Sec Jamis^s Pviudpr* 
Pre/ents^ lift of, p. 423. 

Pritftky^ Dr. on the decoropofition of dep^IogiAicated and inflammable airs, p« 213. 
i'ro^/f/xfj refpe^ng furvivor(bips, p. 248, 253, 256, 258, 261, 263, 265, zSjj 269, 

272. Problems relating to angles, p. 290, 291. 
Prop9fittmsj fundamental, for the condrudion of an hygrometer, p. i. 
* ■ ■— relatiog to infinite ferics, p. 299, 300, 30J, 303, 308, 309, 310, 311^ 

3"» 3U. 
Puhis antimomalis, experiments on, p. 349, 

^ickUme^ pofiefles a great capacity for moifture, p. 4* 

Main^ aBfln£l of a regifter o^ ieept at Lytklon id Rothndflrire, ae Sdutb Lambetil in 
Surrey, and at Selbourn and Pyfcld in Hampihire, for the year 1789, pv 89^ Alefa 
quantity of rain fell in the year 1 788, than in any year fiact ijrso* p* 90* 
Read, Mr. on atmofpheric eledricity, p« x8j« 
Receipts for making fever powders, p. 34^, 347* 
Rennell, Mr. on the rate of travelling, as performed by camels $ and sis applieMtpn, 

as a fcale, fo the porpofes of geography, p. 1 29. 
Refults from a feries of experiments on hygrometry, p. 41 • 

!• Kre, as caufc of hear, the only means of obtaining extreme drynefa, ibid* 

^» Water, in its liquid fhte, the only means of determining the point of extretne 

moiHure on the hygrometer, ibid. 
3. No fibrous or vafcularfubftance, taken length wife, proper for the hygrometer, 
ibid* 

L 1 1 a 4- Lighi 



.[ 436 ] 

4- Light tlirown on the march of a chofen hygrofnetery by comparing it with the 
correfpondent changes in weight of many hygrofcopic fabftancesy ibid. 

^tverjions. See Survk^orJI/ips, 

Ridlington, in Rutland, bed of chalk difcovered near, p. 281. Flints foand about Rid* 

lingt' n not fo black as thofe of the more fouthem counties of England, p. 281* 
Roxburgh^ Dr, on the Chcrmes Lacca, p. 228. 

S. 

Selbourn, in Hampfliire, abftra^l of a regifler 6f rain kept at, for the year 1789, p. 89, 

Series^ infinite, oblervations on, p. 146. Sec Infikite Series, 

'Shoerl, a fubflance common both to bafaltes and granite, p. ^^. 

5o/2///offj of problems relating to furvivorlhips, p. 248, 253, 256, 258, 262, 263, 265^ 

267, 269, 272. Solutions of problems refpeding angles, 0*290, 291. 
Solutions of propofitions relating to infinite feries, p. 299, 3009 302, 303, 309, 31C9 

3IN 3", 3H* 
Squid, a fifh, fuppofed to be the food of the fpermaceti whale, p. 44, 46 
Sfars^ nebulous obfervations on, p. 7i« Milky-way conflfts intirety of fla^s, ibid. 
Sugar, has an affinity with water, and no fenfible one with alcohol, p. 11. Water, 

entering fugar, by the faculty of its capillary pores dilTolves it, ibid. Alcohol, 

entering fugar, by the fame means, evaporates, and leaves the fugar fenfibly as it was 

before, ibid. 
Sulphur of antimony no ways necelTary to the formation of James's powder, p. 360. 
Survi'vor/hips, On the method of determining, from the real probabilities of life, the 

values of contingent teverfions in which three lines are involved in the furvivorfhip, 

p. 246. 

T. 

Tahajheer^ chemical experiments on, p. 368. Hydrabad Tabafheer refembles fragments 
of Cacholong, p. 369. Of a difagreeable earthy tafte, refembling that of magnefis, 
ibid.' Experiments l)n Tabafheer treated with water, p. 370. With vegetable 
colours, 371. At the fire, ibid. With acids, p. 375. With liquid alkalies, p* 37; 
With dry alkalies, p. 379. With other fluxes, p. 380. 
iTahles. 

A table of hygrofcopic and thermofcopic refults, p* 33. 

A table of hygrofcopic refults, on whalebone, quill, and deal, p. 3 ;• 

^Jeteorologicaf journal, principally relating to atmofpheric eledricity, kept st 

Knightlbridge, from May 9, 1789, to May 8, 1790, p. 189— 110. 
Tabic containing a monthly account o^ eledrical fparks, and of pofitiveand nega- 
tive ele(l^rjcity, as indicated by a pith-ball ele^trometeti and fometimes by. onljr 
fiasen threads without balls to them, p. aij. 

Table 



i 

1 



[ 437 3 

Table ftewitig tbe difiance anfwering to any angle from one minute to one degree, 

which is fubtended by anexteniion of a foot, p. 293. 
Table (hewing the difbince anfwering to any angle from one minute to a degreei 

which is fubtended by an extenfion of fix feer, p. 294. 
Tables of fums 6f reciprocals, iifeful in the invcftigaiion of the fummation of 

infinite feries, p. 296, 297, 298^ 299. < 
Table of the comparative changes in the weight and in the length of the fame fub- 
dances, by the fame increafes of moifture, correfpondent to the march of the flip 
of whalebone from 5 to 100 of -its degrees^ p« 409. 
Table of experiments on the comparative changes in the weight and the length 

of the fame fubftance by increafe of moiflure, p. 411. 
Table of the correfpondent marches, by the fame increafes of moiflure, of dif- 
ferent threads, or vegetable and animal fibrous fubfiances taken iengtbwife, 
p. 413. 
Table of the correfpondent marches of flips, or of fibrous vegetable and animal 
fubftances taken acrofs the fibres, and of fuch as have no fenHble fibres, p* 4i5. 
Meteorok)gical journal, kept at the Apartments of the Royal Society, for January 
App. 1790, p. 2. February, p. 4. March| p. 6. April, p. 8. May, p. lo. 
June, p. 12* July, p. 14. Auguft, p. i6. September, p. i8. O^ober, p. 
20. November, p. 22. December, p. 24. 
Table containing the greatef(, leafl, and mean heights of the thermometer and 
barometer; and alfo the mean quantity of rain in inches which fell, for every 
month in the year 1 790, p. 26. 
Tek/cope, defcription of a fimple micrometer for meafuring fmall angles with, p. 285. 
Telefcopical miCTometers* Sec Micrometer. 
Tennant, Smithfon, on the'decompofition of fixed air, p. i82> 
Thermometer, abfb-ad of a regifter of one^ kept at Lyndon in Rutlandfhire, for the year 

1789, p. 89. 
Travelling, on the rate of, as performed by camels, and its application, asa.fca]e, to 
the purpofes of geography, p. 129. Camels will not permit themfelves to be over** 
loaded, ibid* Their hourly rate, in travelling, afcertained, p* 157. 

V. 
Fince^ Rev. Mr. on the invefiigation of infinite fcties, p* 295* 

W. 

fVaring, Dr. on infinite feries, p. 146. 

Heater ^ the only fure immediate means of producing extreme moiflure in hygrofcopte 
bod^s, p. ly 1 6. The temperature of water has a feniible effect on the expanfion 
of ivory, p. I j. The maximum of moifture known by the excefs of water, p. 17* 

a Glafs 



t 



[ 43« ] 

Olifi eoRtftiiif coBcrete witer very imptrh&ljp p. 40t« Water the faufe of moiA 

ture» p.4oat 
X^tf^i fperm«ceti, tmbergrli found la, p. 43. Spermaceti whales, when Snicks 

geiifrall/ void their excrement 1 bur if they do not, ambergris 11 found iAtheoSy p«47» 

Ambergris moft likely to be found in fickly whales, ibid. 
WhaUione hygrometer, defcrlption of, p. 419. 
WQids of Yorkfliire, coniiderable quantities of chalk found in, p. iSt, 

Y. 

TirMfire^ wolds of, confidoable quantities of chalk found ifli p. 2b» 



FROM THE PRESS OF JORN NICHOLS^ 



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144. 18. infirt it 0ftir if 

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